Watching the wonderful things of science is truly cool and amazing. But actually doing the actual experiments yourself will even be more awesome.
Here we compiled some of the best and doable science experiments that you can try doing at home. You just have to carefully follow the procedure of doing it to achieve the expected results.
Warning! Some of the chemicals being used here can really badly hurt you. So please do this with adult supervision or ask your teacher for some guide.
Have fun watching the videos :
12 AMAZING EXPERIMENTS You Can Do at Home
10 Amazing SCIENCE EXPERIMENTS Compilation HD
20 Amazing Science Experiments and Optical Illusions! Compilation
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Showing posts with label Science. Show all posts
Showing posts with label Science. Show all posts
Amazing Science Experiments You can Do at Home Compilation
Science Tech Quiz ( japan )
These are higher-level measurement which may be answered via smartphones, laptop, personal computers using the latest wifi networks or internet broadband technology.
These questions are designed to evaluate your comprehension on several essential topics in technology, science, medical principles and engineering field.
Science Tech Quiz ( new york )
This is an above average level of assessment and analysis done through your or smartphones devices, laptop, personal computers or any latest gadgets. After lessons on Science, Technology and Engineering. Test your knowledge on latest innovation, technologies, discoveries, DNA, Cellular and molecular structure and function.
Determine structures and the functions of each molecule and compound on current technologies and advcacements. Understand the corresponding uses and their importance of each in the next generations.
What's Wrong With the Teenage Mind?
Children today reach puberty earlier and adulthood later.
'What was he thinking?" It's the familiar cry of bewildered parents trying to understand why their teenagers act the way they do.
How does the boy who can thoughtfully explain the reasons never to drink and drive end up in a drunken crash?
Why does the girl who knows all about birth control find herself pregnant by a boy she doesn't even like?
What happened to the gifted, imaginative child who excelled through high school but then dropped out of college, drifted from job to job and now lives in his parents' basement?
If you think of the teenage brain as a car,today's adolescents acquire an accelerator a long time before they can steer and brake. Adolescence has always been troubled, but for reasons the dr somewhat mysterious, puberty is now kicking in at an earlier. andeisthetage. A leading theory points to changes in energy baianuo: Children eat more and move less.
At the same time, first with the industrial revolution and then even more dramatically with the information revolution, children come to take on adult roles later and later. Five hurdled yews ago, Shakespeare knew that the emotionally intense combination of teenage sexuality and peer-induced risk could be tragic.
Exogenic Processes , Weathering, Erosion, Mass Wasting and Deposition
Exogenic Processes
The geological phenomena and processes which occur on and originate from the Earth's surface. These force molds and gives shape to the Earth. The main exogenic processes include weathering, mass wasting, erosion and deposition.
Weathering
Weathering is the break down or dissolving of rocks and minerals on Earth’s surface by different means such as action of water, temperature changes and other activity.
Types of Weathering
1.) Physical ( or Mechanical ) Weathering
It is the process in which the rock is physically broken or disintegrated into smaller pieces due to any physical factors or force ( such as wind, water, ice, sun, etc) without any alteration of its composition.
The following are the major processes that lead to the mechanical weathering of rocks:
a. Frost wedging- when water gets inside the joints, alternate freezing and thawing episodes pry the rock apart. The water expansion pushes the rock apart.
b. Salt crystal growth- force exerted by salt crystal that formed as water evaporates from pore spaces or cracks in rocks can cause the rock to fall apart
c. Abrasion – wearing away of rocks by constant collision of loose particles
c. Exfoliation/Unloading - peeling away of large sheets of loosened rock materials
d. Biological Activities - caused by an organism’s activity such as plant roots, burrowing animals & humans
e. Friction and impact
f. Temperature changes
The sudden cooling of a rock surface may cause it to contract so rapidly over warmer rock beneath that it flakes or grains break off. This usually happens in deserts, where intense daytime heat is followed by rapid cooling after.
Chemical Weathering
It is the process that decomposes rocks through chemical reactions that alters the composition of the original rock-forming minerals.
The following are the main processes that leads to chemical weathering :
a. Dissolution – dissociation of molecules into ions such as dissolution of limestone in acidic water. This process is sometimes called carbonation.
Ex. sinkholes, caves ; CO2 + rainwater = Carbonic Acid
b. Oxidation- when minerals in rocks react with the oxygen dissolved in water
Ex. water + iron + oxygen = iron oxide (rust)
c. Hydrolysis- reaction between minerals and the water itself. Ex. calcites in caves
c. Living organisms - Lichens that grow on rocks produce weak acids that chemically weather rock.
d. Acid rain - compounds from burning coal, oil and gas react chemically with water forming acids. Acid rain causes very rapid chemical weathering
Factors that affect the rate, type and extent of weathering
a. Climate – areas that are cold and dry tend to have slow rates of chemical weathering and weathering is mostly physical; chemical weathering is most active in areas with high temperature and rainfall.
b. Rock type – the minerals that constitute rocks have different susceptibilities to weathering. The susceptibility of minerals (from high to low) roughly follows the inverse of the order of crystallization of minerals in the Bowen’s reaction series. Thus, olivine which crystallizes first is the least resistant whereas; quartz which crystallizes last is the most resistant.
c. Rock structure- rate of weathering is affected by the presence of joints, folds, faults, bedding planes through which agents of weathering enter a rock mass. Highly jointed/ fractured rocks disintegrate faster than a solid mass of rock of the same dimension
d. Topography- physical weathering occurs more quickly on a steep slope than on a gentle one. On a gentle slope, water may stay longer in contact with the rocks, hence chemical weathering is enhanced.
e. Time- length of exposure to agents of weather determines the degree of weathering of a rock. The longer time of exposure to agents of weathering results to higher rate of weathering.
Mass Wasting
Mass wasting is the process of downslope movement of rock, regolith, sand and soil under the direct influence of gravity. It is also known as mass movement or slope movement.
It moves materials from higher to lower elevations. The streams or glaciers can then pick up the loose materials and eventually move them to a site of deposition.
Types of Mass Wasting
They are classified based on what materials are involved, the type of movement, and the rate of movement and are controlled by the slope angle, water saturation, and presence of clay. These are classified into two broad categories: slope failures and sediment flow.
A.) Slope failures
Slope failures are sudden failure of the slope that results to the transport of debris downhill by sliding, rolling, and slumping.
1. Slump. It is a type of slide wherein downward rotation of rock or regolith occurs along a curved surface. Slump usually results when the geometrical stability of a slope is compromised by the undercutting of its base, such as by wave action, a meandering river, or construction.
2. Rock fall and debris fall. These are the result of free falling of bodies of rocks that break loose or a mixture of rock, regolith, and soil in the case of debris fall. Rockfalls occur when pieces of rock dislodge from a steep rock face or cliff.
3. Rock slide and debris slide. It involves the quick displacement of masses of rock or debris along an inclined surface.
4. Landslide. A type of mass movement from a sudden rapid event in which large quantities of rock and soil plunge down steep slopes. This includes all downslope movement whether it be bedrock, regolith, soil, or a mixture of these.
B.) Sediment flow
In sediment flows, materials flow downhill mixed with water or air; Slurry and granular flows are further subdivided based on velocity at which flow occurs
1. Slurry flow – water-saturated flow which contains 20-40% water; above 40% water content, slurry flows grade into streams
• Solifluction – common wherever water cannot escape from the saturated surface layer by infiltrating to deeper levels; creates lobes and sheets of debris. The flow of water-saturated earth material over an impermeable surface such as permafrost.
• Debris flow – results from heavy rains causing soil and regolith to be saturated with water; commonly have a tongue-like front; Debris flows composed mostly of volcanic materials on the flanks of volcanoes are called lahars.
• Mud flow – highly fluid, high velocity mixture of sediment and water; can start as a muddy stream that becomes a moving dam of mud and rubble; differs with debris flow in that fine-grained material is predominant;
2. Granular flow
Granular flows contains low amounts of water, 0-20% water; fluid-like behavior is possible by mixing with air
• Creep – slowest type of mass wasting requiring several years of gradual movement to have a pronounced effect on the slope ; evidence often seen in bent trees, and offset in roads and fences. Creep occurs when regolith alternately expands and contracts in response to freezing and thawing, wetting and drying, or warming and cooling.
• Earth flow – involves fine-grained material such as clay and silt and usually associated with heavy rains or snowmelt; tend to be narrow tongue-like features that that begin at a scarp or cliff
• Grain flow – forms in dry or nearly dry granular sediment with air filling the pore spaces such as sand flowing down the dune face
• Debris avalanche – very high velocity flows involving huge masses of falling rocks, debris, soil, and trapped air racing down in very steep mountain ranges. The rock and debris break up and pulverize on impact.
Events that cause mass wasting processes
a. Shocks and vibrations
Earthquakes and minor shocks such as those produced by man-made explosions and passage of heavy trucks on the road
b. Slope modification
This creates artificially steep slope thus it is no longer at the angle of repose
c. Undercutting
Made by streams eroding banks or surf action undercutting a slope
d. Changes in hydrologic characteristics
Heavy rains may lead to water-saturated regolith thereby increasing its weight, and reducing grain to grain contact and the angle of repose;
e. Changes in slope strength
Constant weathering weakens the rock and leads to slope failure;
Vegetation holds soil in place and slows the influx of water;
The tree roots further strengthen slope by holding the ground together
f. Volcanic eruptions
They produce shocks; thereby causing the production of large volumes of water from melting of glaciers during eruption, resulting to mudflows and debris flows
Erosion and Deposition
Erosion is the geological process that transports material by a mobile agent such as water, wind, or ice (usually in the form of glacier). It is the action of surface processes that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location.
Deposition is the exogenic process that happens after erosion. This process adds sediments, soil and rocks to a landform or land mass.
1. Water deposition
Where a river meets the ocean is called the mouth of the river. Soil carried by a river is deposited at the mouth and new land is formed. This new soil-rich land is known as a delta.
2. Wind Deposition
Sand dunes are large deposits of sand dropped when the wind stopped blowing. The location of the sand dunes shifts frequently.
3. Glacial Deposition
When glaciers melt, they drop or deposit the rocks they were carrying.
Forces That Cause Erosion
1.) Water
This is considered to be the main cause of erosion on Earth. Some of the ways that water causes erosion are by :
Rivers and Streams. They create a significant amount of erosion since they break up particles along the river bottom and carry them downstream. One great example of river erosion is the Grand Canyon which was formed by the Colorado River.
Stream - a body of running water, confined to a channel that runs downhill under the influence of gravity.
• Headwaters - upper part of stream near its source in the mountains
• Mouth - place where a stream enters sea, lake or larger stream
• Channel - a long, narrow depression eroded by a stream into rock or sediment
• Stream banks - sides of channel
• Streambed – channel bottom
Drainage basin - the total area drained by a stream and its tributaries
Tributary - a small stream flowing into a larger one
Drainage pattern - the arrangement, in map view, of a stream and its tributaries
a. Dendritic - drainage pattern resembling the branches of a tree
b. Radial pattern - streams diverge outward like the spokes of a wheel
c. Rectangular pattern - tributaries have frequent 90° bends and join other streams at right angles
d. Trellis pattern - parallel streams with short tributaries meeting at right angles
Stream Erosion
Stream velocity controlled by stream gradient (slope), channel shape and channel roughness.
Streamflow erosion occurs by :
Abrasion, the process of sediments wearing down the bedrock and the banks
Attrition, collision between sediments breaking into smaller more rounded pebbles
Hydraulic action, the force of water against the banks compressing air pockets into cracks, which expand and fracture the rock over time
Solution, the process of dissolving soluble sediment by action of acidic water
Floodplain - flat valley floor composed of sediment deposited by the stream.
Canyons - large valleys created by a river or stream
Sediment Transportation
Sediment load transported by a stream can be subdivided into:
1. Bed load - large or heavy particles that travel on the streambed.
2. Suspended load - sediment that is small/light enough to remain above the stream bottom by turbulent flow for an indefinite period of time.
3. Dissolved load - dissolved ions produced by chemical weathering of soluble minerals upstream.
Sediment Deposition
Sediments are temporarily deposited along stream course as bars and floodplain deposits, and at/near its end as deltas or alluvial fans
• Bars - ridges of sediment (usually sand or gravel) deposited in the middle or along the sides of a stream.
• Braided streams - contain sediment deposited as numerous bars around which water flows in highly interconnected rivulets.
• Delta - body of sediment deposited at the mouth of a river when flow velocity decreases
• Alluvial fan - large, fan- or cone-shaped pile of sediment that forms where stream velocity decreases as it emerges from a narrow mountain canyon onto a flat plain.
Flood - occurs when water overflows or inundates land that's normally dry. Most common is when rivers or streams overflow their banks.
Ocean or Sea waves. They can cause the erosion on coastlines. The shear energy and force of the waves causes pieces of rock and coastline to break off changing the coastline over time. Waves are caused by wind
Three factors that affects the wave:
1. Wind speed - the greater the wind speed, the larger the waves.
2. Wind duration - the greater the duration of the wind (or storm) the larger the waves.
3. Fetch - the greater the fetch (area over which the wind is blowing - size of storm) the larger the waves.
Types of waves
Constructive waves Destructive waves
Low energy High energy
Long wavelength Short wavelength
Stronger swash Strong backwash
Built coast/ beach Erode coast/beach
Waves behaviour
1. Reflection waves - bounce off
2. Refraction waves - change in direction
3. Diffraction waves - bend through an opening
4. Interference - waves affect each other
5. Resonance - slash and fro
Beach - a landform along the coast of an ocean, sea, lake or river; it is formed by constructive waves.
Parts of a Beach
1. Marine terrace - sloping platform that maybe exposed at low tide
2. Beach face - section exposed to wave action
2. Wrack line - organic and inorganic debris is deposited by wave action
3. Berm - a wave-deposited sediment platform that is flat or slopes slightly landward
4. Spit - fingerlike ridge of sediment that extends out into open water formed by long shore drift
5. Bay-mouth bar - a ridge of sediment that cuts a bay off from the ocean which is formed by sediment migrating across what was earlier an open bay
6. Tombolo - a bar of sediment connecting a former island to the mainland
Coast - the area where land meets the sea or ocean.
• Coastal Landforms – Cliff retreat
A wave cut platform is the platform that’s left behind as the cliff retreats.
• Headlands and Bays
Headland and bays form where there are alternating bands of resistant (hard rock) and less resistant (soft rocks) along a coast.
Coves
Cove is a wide, circular bay with a narrow entrance. They form where there’s a band of hard rock along a coast with a band of softer rock behind it.
2.) Wind
Wind is one type of erosion that occurs especially in dry areas. Wind can erode by picking up and carrying loose particles and dust away (called deflation).
It can also erode when these flying particles strike the land and break off more particles (called abrasion).
Soil Movements Due to Wind Erosion
Suspension This moves fine particles (less than 0.1 mm) of dirt and dust over long distances.
Saltation This process moves soil particles (0.1 – 0.5 mm) across a surface by a series of short bounces along the surface of the ground, and dislodging additional particles with each impact. It is the primary means of soil movement.
Creep It occurs when larger soil particles (0.5 – 1 mm) slide and roll over an area and meet particles that have been through saltation.
3.) Glaciers
Glacier is defined as a moving body of ice on land that moves downslope or outward from an area of accumulation. They are giant rivers of ice that slowly move carving out valleys and shaping mountains.
Glaciers move to lower portions and elevations by means of plastic flow because of the great stress on the ice at depth, and basal slip. This is facilitated by meltwater which acts as lubricant between the glacier and the surface over which it moves.
The velocity of a glacier is lowest near the base and where it is in contact with valley walls; but the velocity is highest near the top center of the glacier.
It is part of a subsystem of the hydrosphere known as the cryosphere. The cryosphere is those portions of Earth's surface where water is in solid form, including sea ice, lake ice, river ice, snow cover, glaciers, ice caps.
Types of glaciated terrain on the Earth’s surface
a. Alpine glaciation is found in mountainous regions.
b. Continental glaciation exists where a large part of a continent (thousands of square kilometers) is covered by glacial ice.
c. Valley glacier is a glacier that is confined to a valley and flows from a higher to a lower elevation.
Geological features created by glaciers:
a. ArĂȘte - steep ridge formed by two glaciers
b. Cirque - bowl shaped landform in the side of a mountain.
c. Horn - pointy shaped mountain peak.
d. Moraine - accumulation of material called till left behind by glacier.
4. Groundwater
Is the water found underground, in the cracks and spaces, in soil, sand and rocks.
Three types of groundwater
a. Meteoric water - water derived from precipitation; rain droplets that seeps down into spaces between the rocks.
b. Connate water - water that contains many mineral components that were trapped in the pores of sedimentary rocks.
c. Magmatic water - water which was formerly chemically bound up and has been released by heating in volcanic processes.
Subsurface water - water in a soil mantle that is divided into two zones:
1. The unsaturated zone (zone of aeration) - the soil pores are only partially saturated with water.
These have three subzones:
a. Soil water zone - water readily available for plants
b. Intermediate zone - use in irrigation
c. Capillary fringe - layer in which groundwater seeps up from a water table by capillary action to fill pores.
2. The saturated zone (zone of saturation) which includes ground water.
This is classified into 4 categories:
a. Aquifer - an underground layer of water-bearing permeable rock. ex. deposits of sand and gravel
Types of Aquifer
1. Unconfined Aquifer (phreatic aquifer) - When water can flow directly between the surface and the saturated zone of an aquifer.
2. Confined Aquifer (artesian aquifer) - A water- bearing subsurface stratum that is bounded above and below by formations of impermeable, or relatively impermeable soil or rock.
b. Aquiclude - a solid, impermeable area underlying or overlying an aquifer; it can absorb water but cannot transmit it in significant amount. Ex clay
c. Aquifuge - An impermeable body of rock which contains no interconnected openings and therefore neither absorbs nor transmits water. Ex. massive compact rock
d. Aquitard - A bed of low permeability adjacent to an aquifer; may serve as a storage unit for groundwater, although it does not yield water readily. Ex. sandy clay
Organic Compounds : Carbon Atom, Hydrocarbons Bonding & Naming, Sigma & Pi bonds , and Hybridization
Organic compound is a compound in which one or more atoms of carbon are covalently linked to atoms of other elements, most commonly hydrogen, oxygen, or nitrogen.
The Carbon Atom
Carbon is a nonmetallic tetravalent element making four electrons available to form covalent chemical bonds. Carbon is the only element that can form so many different compounds because each carbon atom can form four chemical bonds to other atoms. This makes carbon unique among the other elements.
Reasons for having many carbon compounds:
• carbon has the ability to form long carbon-to-carbon chains
• carbon atoms can bind to each other not only in straight chains but in complex branchings
• carbon atoms can share electrons to form single, double or triple bond
• with same collection of carbon atoms and bonds, isomers can be formed
• all of the electrons that are not being used to bond carbon atoms together into chains and rings can be used to form bonds with atoms of several other elements
Bonding Patterns in Hydrocarbons
Hydrocarbons are molecules that contain only carbon and hydrogen. Due to carbon's unique bonding patterns, hydrocarbons can have single, double, or triple bonds between the carbon atoms. The bonding of hydrocarbons allows them to form rings or chains.
Hydrocarbons are classified as either aliphatic or aromatic . Aliphatic described hydrocarbons derived by chemical degradation of fats or oils. Aromatic hydrocarbons described hydrocarbons derived by chemical degradation of certain pleasant-smelling plant extracts. Aliphatic hydrocarbons are divided into alkanes, alkenes, and alkynes. Alkanes have only single bonds, alkenes contain a carbon-carbon double bond, and alkynes contain a carbon-carbon triple bond. Aromatic hydrocarbons are those that are significantly more stable than their Lewis structures would suggest; i.e., they possess “special stability.” They are classified as either arenes, which contain a benzene ring as a structural unit, or nonbenzenoid aromatic hydrocarbons, which possess special stability but lack a benzene ring as a structural unit.
Illustration: H H
Alkane : Ethane H-C – C- H with single bond between C atoms
H H
Alkene: Ethene H H with double bond between C atoms
C=C
H H
Alkyne: Ethyne H – C = C- H with triple bond between C toms
Naming of Hydrocarbon
Some Prefixes Used in Naming Aliphatic Hydrocarbon:
Number of C Prefix Number of C Prefix
1 meth- 6 hex-
2 eth- 7 hept-
3 prop- 8 oct-
4 but- 9 non-
5 pent- 10 dec-
Naming of Hydrocarbon
I. Alkane: prefix + ane
Example : 5-carbon alkane : pentane
II. Alkene: prefix + ene
Example: 5-carbon alkene: pentene
III.Alkyne: prefix + yne
Example: 5-carbon alkyne: pentyne
Naming of of Cycloalkanne
Example 1: cyclo + name of alkane
H H
C Name: cyclopropane
H - C C - H
H H
Alkyl
It is an alkane minus one hydrogen. In naming alkyl, replace -ane with –yl of the alkane’s name.
Example: alkane alkane structure alkyl alkyl structure
H H
methane H – C – H methyl H – C - H H
IUPAC Rules for Alkane Nomenclature
1. Find and name the longest continuous carbon chain.
2. Identify and name groups attached to this chain.
3. Number the chain consecutively, starting at the end nearest a substituent
group.
4. Designate the location of each substituent group by an appropriate number
and name.
5. Assemble the name, listing groups in alphabetical order. The prefixes di, tri,
tetra etc., used to designate several groups of the same kind, are not
considered when alphabetizing.
Illustration: Name the following organic compound represented by dot-line structure.
A. 4 2
5 3 1 answer: 2-methylpentane
Cl
B. 6 4 2
5 3 1 answer: 3-chloro-2,4 -dimethylhexane
IUPAC Rules for Alkene and Alkyne Nomenclature
1. Identify the longest carbon chain that contains both carbons of the double or triple
bond.
2. The carbon backbone is numbered from the end that yields the lowest positioning for
the double or triple bond.
3. Substituents are added to the name as prefixes to the longest chain.
4. The position of the double or triple bond is indicated using the position of the carbon in
the bond with the lower backbone number, and the suffix for the compound is
changed to “-ene” for an alkene and “-yne” for an alkyne.
Illustration 1: Name the following organic compound:
Solution:
Assign the lowest number to the double bond
5 3 1
4 2 answer: 2-pentene
Illustration 2: Name the following organic compound
answer: 4-chloro-6-diiodo-7-methyl-2-nonyne
When there are two double or triple bonds in the molecule, find the longest carbon chain including both the triple bonds. Number the longest chain starting at the end closest to the double or triple bond that appears first. The suffix that would be used to name this molecule would be - diene for 2 double bond and –diyne for two triple bonds. For example:
1 3 5 7
name: 4-methyl-1,4-octadiyne
2 4 6 8
Lesson 9.4 Sigma Bond and Pi Bond
Sigma bond is a covalent bond resulting from the formation of a molecular orbital by the end-to-end overlap of atomic orbitals Denoted by the symbol Ï.
Pi bond is a covalent bond resulting from the formation of a molecular orbital by side-to-side overlap of atomic orbitals along a plane perpendicular to a line connecting the nuclei of the atoms. Denoted by the symbol Ï.
Locating Ï and Ï bond
Ï - bonds
C C C C C C
Ï - bonds
Example: How many sigma and pi bonds are there in ethene ?
Hybridization
Hybridization is the fusion of atomic orbitals to form newly hybridized orbitals, which in turn, influences molecular geometry and bonding properties. Hybridization is also an expansion of the valence bond theory. Three types of hydrocarbon compounds will be utilized to illustrate sp3, sp2, and sp hybridization.
Hybridization of Ethane
Ethane is a two carbon molecule with a single-bond between the two carbons To understand the hybridization, consider the orbital diagram of the unhybridized valence electrons of unhybridized carbon.
Carbon has four valence electrons, two in the 2s orbital and two more in three 2p orbitals In ethane molecule, carbon needs to make four single bonds, one to the other carbon atom and three more to the hydrogen atoms. Single bonds can only be made with s-orbitals or hybrid orbitals, and as it stands carbon can not make four bonds. To rectify this the atomic orbitals go through a mixing process called hybridization, where the one 2s and the three 2p orbitals are mixed together to make four equivalent sp3hybrid orbitals . One s orbital and 3 p-orbitals were used in this case, and the result is a total of four sp3 hybrids. The four electrons are then distributed equally among them.
There are two types of orbitals with two types of shapes. A s type orbital is a sphere of electron density around an atom. Hybrids and sorbitals can make sigma type bonds where the electron density is shared directly between the atoms. The other type, p-orbitals, have two lobes above and below the plane of the atom. They are used to make Ï bonds, which make up double and triple bonds.
sp3 hyrbid orbital
Shown above is the sp3 orbital used by the carbon to make the sigma bond with the adjacent carbon. There are three things to notice:
1) The bulk of the electron density is directly between the two carbon atoms, indicative of a sigma bond.
2) The shape of the hybrid matches what orbitals were used to make it. For this case, sp3 hybrids are 3 parts p orbitals and 1 part s orbital. The end result is an orbital that is mostly p shaped but it a little bit lop-sided.
3) sp3 hybrids take a tetrahedral geometry with an angle between them of 109.5 degrees. Click on one of the ethane pictures above and rotate the 3D image until you can see this geometry.
Hybridization of Ethylene
Unlike methane, ethylene is shaped differently, despite the fact that the carbon in ethylene has the same electron configuration. Evidence shows that the carbon in an ethylene molecule is sp2 hybridized. This means that 1 s orbital is being mixed with 2 p orbitals.
The energy diagram setup this time is different because only 2 p orbitals are being mixed. While creating the energy diagram, be sure not to make mistake as shown at the above right figure. By placing two electrons in the same orbital, Hund's rule is violated. The said rule states that all orbitals among the same energy levels have to be filled with at least one electron before being paired up again. The 2p orbital here is considered low enough energy to be classified within the same energy level as the sp2 orbitals. The figure below portrays the correct way to distribute your electrons.
Notice how that lone electron in the 2p orbital is separate from the electrons in the sp2 orbitals. This is what influence ethylene's shape. The lone electron from each carbon will remain in its respective p orbital and form a pi bond with the other p orbital electron. Thus, ethylene is a planar molecule, with orbitals spaced 120 degree angles apart.
Hybridization of Acetylene ( or ethyne )
Acetylene is an sp molecule. This means that 1 s orbital is being mixed with 1 p orbital. The energy diagram for this setup is shown below::
The lone electrons in the 2p orbitals are not part of the sp orbitals. Instead, each electron is in its respective p orbital, and will bond with its respective p orbital of the other carbon. This in itself will create a sigma bond and two pi bonds, leading to the formation of a linear molecule.
In Lewis structure, acetylene is comprised of 2 triple-bond carbons. The bond angle is 180 degrees, indicative of a linear molecule.
Endogenic Processes , Deformation of the Earth's Crust , Continental Drift & Plate Techtonics
Endogenic Processes
The geological phenomena and processes which is located, formed or occurring beneath the Earth's surface. These processes are the reasons behind major landform features.
The principal energy sources for endogenic processes are:
1. heat in Earth’s interior
2. the redistribution of material in the earth’s interior according to density
Heat in Earth’s interior
The earth’s deep heat originates chiefly from radiation. The continuous generation of heat in the earth’s interior results in the flow of heat toward the surface. With the proper combination of materials, temperature, and pressure, chambers and layers of partial melting may occur at certain depths within the earth.
Experts have estimated the internal temperature of the Earth from geotherm curve. It can be deduced that the mantle is considerably hotter than the crust, and the core is much hotter than the mantle.
- Core-mantle boundary: 3,700°C
- Inner-core – outer-core boundary: 5,000°C±500°C
- Earth’s center: 6,400°C±600°C
Magma Formation
The primary source of magma formation is the asthenosphere. It is the layer in the upper mantle where convection currents may arise from and move to the lithosphere.
Magma is formed when hot rocks in the Earth partially melt which occurs when
(1) the pressure decreases,
(2) when volatiles are added to hot rocks and
(3) when heat is transferred by a magma rising from the mantle into the crust.
Magma chambers form in the crust itself due to influence of the heat flow or under the direct influence of the heat carried by rising abyssal magma. When magma reaches the near surface parts, it may form variously shaped intrusive bodies or can be extruded onto the surface, in the form of volcanoes.
VOLCANO
Volcano is a point on the earth’s crust where magma forces its way to the surface
Magma - the mixture of molten rock, suspended mineral grains and dissolved gases that form in the crust or mantle when temperature are sufficiently high.
Three types of magma
1. Basaltic magma - contains about 50% SiO2 and very little dissolved gas. The two common igneous rock derived from basaltic magma are basalt and gabbro.
2. Andesitic magma - contains about 60% SiO2, and lot of dissolved gas, andesite and diorite are the common IR
3. Rhyolithic magma - contains about 70% SiO2 and the highest gas content. The two common igneous rock derived from rhyolithic magma are rhyolite and granite.
Types of Volcano Based on Shape
1. Cinder Cone - the simplest type of volcano, cinder falls around the vent to form a circle or oval cone. Examples: Sunset Crater, Arizona and Taal Volcano
2. Composite Volcano - Steep –sided, symmetrical cones.
Examples: Mt. Fuji, Japan and Mt. Mayon, Philippines
3. Shield Volcanoes - a sloping dome shape like a warriors shield.
Examples: Mauna Loa, Hawaii and Kilauea, Hawaii
Types of a Volcano based on Volcanic Activity
1. Active - eruptions can be anytime and often.
2. Dormant - has been a while since it has erupted, but could at anytime.
3. Extinct -it hasn't erupted in a very long, long time so it probably won't ever again.
Calderas - collapsed volcanoes
1. Magma chamber has emptied and the ground has sunk often becomes a lake
2. New volcanoes can form, or pressure can build from below, lifting the ground
3. If acidic, this can cause a catastrophic eruption in the form of a ”super-volcano”
Ex. Santorini and Mt. Pinatubo
Where does magma occur?
• On subduction zones
• On constructive plate boundaries
• On hot spots
Hotspots
Hotspots are caused by the upwelling of super heated rocks in the mantle plumes
Ex: Hawaii – basic Yellowstone - acid
Volcanic Explosivity index (VEI)
1 – Hawaiian gentle Kilauea
2 – Strombolian explosive Stromboli
3 – Vulcanian severe
4 – PelĂ©an cataclysmic Mt.PelĂ©e
5 – Plinian paroxysmal St.Helens
6 – plinian/ultra-plinian colossal Krakatoa
7 – ultra-plinian super-colossal Tambora
8 – supervolcanic mega-colossal Yellowstone
*Number 8 has never been experienced in human history.
Volcanic hazards
1. lava flows
2. pyroclastic flow
3. ash clouds
4. lahars
5. lava bombs
EARTHQUAKE
Earthquakes are the shaking, rolling or sudden shock of the earth’s surface caused by a sudden release of strain in the earth's interior.
Gravitational differentiation has also led to the stratification of the earth into geospheres of varying density. Is also manifested in the form of tectonic movements , which, in turn, lead to the tectonic deformation of crustal and upper mantle rocks.
The accumulation and subsequent discharge of tectonic stresses along active faults causes earthquakes.
Some Terms Related To Earthquake
Focus (Hypocenter) - the site of the first movement on a fault and the center of energy release.
Epicenter - point on the Earth’s surface that lies vertically above the focus.
Fault / Geological Fault - is a fracture in the ground or rock strata with its two adjacent surfaces along the plane of fracture.
Related image
Seismic waves, which are produced due to earthquake, is divided into two:
1. Body waves - travels through the interior(body) of earth as they leave the focus
P waves (primary waves) – first recorded in a seismograph; type of seismic waves that arrive at the surface first and move by compressing and expanding the ground like an accordion; can travel through solid, liquid and gas.
S waves (secondary waves) – slower than P waves thus recorded later.
2. Surface waves - travels parallel to the earth’s surface and these waves are slowest and most damaging.
Love waves - It moves the ground from side to side in a horizontal plane but at right angles to the direction of propagation
Rayleigh waves - wave move both vertically and horizontally in a vertical plane pointed in the direction in which the waves are travelling.
Instruments used to detect earthquake
1. Seismograph - a sensitive instrument that measures and record seismic waves.
2. Richter scale - is used to rate the magnitude of an earthquake (that is the amount of energy released during an earthquake.)
3. Mercalli intensity scale - is a seismic scale used for measuring the intensity of an earthquake.
Lesson 9.2 – Deformation in the Earth’s Crust
I. Deformation of rocks in Earth's crust takes many forms;
A. Changes in volume, shape, and position may occur alone or in combination.
1. Stress = applied force = cause of the deformation
Types of stress
1) Tensional-stretching,
-increased volume
2) Compressional
- squeezing,
decreased volume
3) Shear - change in shape
2. Strain (resulting deformation)
a. Elastic - recoverable, small amounts of strain,
doesn’t happen to rocks
b. Plastic - permanent;
rocks flow as movement occurs along small structural defects.
3. Fracture (Brittle deformation) - rupture
rock moves in opposite directions on either side of a break.
B. Causes of deformation
1. Confining pressure - due to the load of overlying rocks
2. Stresses applied at plate boundaries
- usually not uniform instead this is directed pressure
II. Strike and dip are used to describe the orientation of planar features.
A. Outcrop - site where rocks are exposed at the surface
B. Dip - the angle of inclination of the bedding surface down off the horizontal
C. Strike - the trend or direction of the strata or the bearing of any horizontal
line on the plane perpendicular to the direction of dip.
III. Features of plastic deformation - Folds
Folds
Folds are wavelike undulations caused by bending of rocks usually produced by horizontal compressive stresses. It occurs at great depths inside the Earth under great temperatures and pressures.
Anatomy of Fold
1.Axial plane - a plane through a rock fold that includes the axis-divides the fold as symmetrically as possible.
2. Axis - the ridge or place of sharpest folding.
3. Limb - 1 of 2 parts of the fold-on either side of axis.
4. Plunge - angle that fold axis makes with the horizontal
Types of folds
Monocline - double flexure of rock layers. This is the simplest type of fold.
This fold involves a slight bend in otherwise parallel layers of rock.
Anticline - arching or upwarping of rock layers.
It is a convex up fold in rock that resembles an arch like structure with the rock beds (or limbs) dipping way from the center of the structure.
Syncline- downwarping of rock layers .
This is a fold where the rock layers are warped downward. Both anticlines and synclines are the result of compressional stress.
Dome - non-linear, anticlinal fold-beds dip away from central area in all directions
Basin - non - linear, synclinal fold-beds dip towards central area from all directions.
More complex fold types can develop in situations where lateral pressures become greater.
The greater pressure results in anticlines and synclines that are inclined and asymmetrical.
Recumbent fold - develops if the center of the fold moves from being once vertical to a horizontal position.
Recumbent folds are commonly found in the core of mountain ranges and indicate that compression and/or shear forces were stronger in one direction.
Faults
Faults are breaks in rock mass where appreciable movement of rocks on opposite sides of the break has occurred.
Faults are formed in rocks when the stresses overcome the internal strength of the rock resulting in a fracture. Faults occur from both tensional and compressional forces.
a. Hanging wall - block of rock immediately above fault surface
b. Footwall - block of rock immediately below fault surface
Types of Fault
Faults are classified by type of stress that acts on the rock and by the nature of the movement of the rock blocks either side of the fault plane.
1. Dip-slip faults - movement of the two blocks is up and down the dip of the fault-primarily vertical
a. Normal fault - footwall moves up with respect to hanging wall (associated with tensional stress); occurs in Divergent plate boundary.
Normal faults occur when tensional forces act in opposite directions and cause one slab of the rock to be displaced up and the other slab down.
Reverse/ thrust fault - footwall moves down with respect to hanging wall (associated with compressional stress and usually lots of folding); occurs in Convergent plate boundary.
Reverse faults develop when compressional forces exist. Compression causes one block to be pushed up and over the other block.
c. Graben fault - produced when tensional stresses result in the subsidence of a block of rock. On a large scale these features are known as Rift Valleys.
Horst fault - the development of two reverse faults causing a block of rock to be pushed up.
Graben and horst - features characterized by down-dropped and uplifted blocks of rock, respectively, bordered by pairs of normal faults.
2. Strike-slip faults - movement of the two blocks on either side of the break is along the strike and dominantly horizontal (associated with shear stress); occurs in Transform fault boundary.
Left-lateral strike-slip fault (sinistral)
It is one on which the displacement of the far block is to the left when viewed from either side.
Right-lateral strike-slip fault (dextral)
It is one on which the displacement of the far block is to the right when viewed from either side.
The San Andreas Fault in California is a right lateral strike-slip transform fault.
The West Valley Fault (WVF) is one of the two major fault segments of the Valley Fault System.
It runs through Metro Manila to the cities of
Marikina, Quezon City ,
Pasig , Makati ,
Taguig and Muntinlupa
It moves in a dominantly dextral strike-slip motion.
Lesson 9.3 – Continental Drift
The continental drift hypothesis was first articulated by Alfred Wegener, a German meteorologist, in 1912. He proposed that a single supercontinent, Pangaea, separated into the current continents and moved across Earth’s surface to their present locations.
In 1915, he published his work through a book entitled ‘The Origin of Continents and Oceans’ .
Scientists were reluctant to believe that continents could drift. During the 1950s-60s, it was still widely held that that continents and ocean basins had fixed geographic positions.
During the 1960s, advances in oceanography generated a lot of new data. They found out that the ocean floor was characterized by deep depressions called trenches and a network of ridges that encircled the globe.
Together with heat flow measurements, these topographic data led to the emergence of the Seafloor Spreading Hypothesis. This findings in turn revived interest in Alfred Wegener’s idea of drifting continents.
Evidences supporting Continental Drift
• The fit of the continents
- Opponents of Wegener’s idea disputed his continental fit evidence, arguing that the fit of the continents’ margins was crude, and that shorelines were continuously being modified by wave erosion and depositional processes.
- A perfect fit could not be achieved. The process of stretching and thinning of the continental margins and sedimentary processes could explain some of the overlaps.
• Similarity in geological units and structure
- rocks on both sides of the Atlantic Ocean were identical in terms of type and age.
- mountain ranges with the same rock types, structures, and ages, that were now on opposite sides of the Atlantic Ocean.
The Appalachians of the eastern United States and Canada, for example, were just like mountain ranges in eastern Greenland, Ireland, Great Britain, and Norway.
Wegener concluded that they once formed a single mountain range that just became separated.
• Fossil match
- Similar fossils of extinct plants and animals in rocks of the same age were found on different continents, which are now separated by large bodies of water.
Organisms were adapted to a specific type of environment and their dispersal could be limited by biogeographic boundaries (e.g. oceans, mountain ranges, etc.)
Wegener argued that these organisms could not have physically crossed the oceans; rather, the continents were in fact part of a large contiguous landmass which later on broke apart and drifted.
• Glacial and paleoclimate evidence
- Wegener analyzed glacial tills and striations of ancient times and found out that glaciers
of the same period (late Paleozoic age, around 300 million years ago) are located in
Australia, South America, Africa, India, and Antarctica.
Except for Antarctica, these countries did not have subpolar climate that allowed glaciation.
Putting the continents together in accordance to Wegener’s Pangaea shows that the glaciation only occurred in a small region in Gondwana (around the South Pole) which then moved outward to the aforementioned continents.
His studies showed that South Africa was originally at the South Pole, which explains the flow direction of the ancient glaciers.
Fitting the continents together places the northern half of Pangaea closer to the tropics and was proven correct by fossil and climatological evidences.
Lesson 9.4 – Plate Tectonics
Seafloor spreading hypothesis
Harry Hess advanced the theory of seafloor spreading during the 1960s. He proposed that seafloor separates at mid-ocean ridges where new crust forms by upwelling magma.
Newly formed oceanic crust moves laterally away from the mid-ocean ridge with the motion like that of a conveyor belt. Old oceanic crusts are dragged down at the trenches and re-incorporated back into the mantle.
Proof for seafloor spreading
- Magnetic stripes on the seafloor: detailed mapping of magnetism recorded in rocks of the seafloor shows that these rocks recorded reversals in direction and strength of the Earth’s magnetic field. Alternating high and low magnetic anomalies run parallel to mid ocean ridges. Pattern of magnetic anomalies also matches the pattern of magnetic reversal already known from studies of continental lava flows.
Theory of Plate Tectonics
Plate Tectonics states that the Earth’s outermost rigid layer (lithosphere)is broken into discrete plates which are moving more or less as a unit. The process is mostly driven by mantle convection, the lithospheric plates ride over the soft, ductile asthenosphere. Gravity also accounts since dense plates slips beneath less dense plates.
The different types of lithosphere at plate boundaries and their relative movements create the distinctive sets of geologic features.
Concept of lithospheric plate
a. The lithosphere consists of the crust and the uppermost mantle.
- Average thickness of continental lithosphere : 150km
- Average thickness of old oceanic lithosphere : 100km
b. Composition of both continental and oceanic crusts affect their respective densities.
c. The lithosphere floats on a soft, plastic layer called asthenosphere.
d. Most plates contain both oceanic and continental crust; a few contain only oceanic crust.
e. A plate is not the same as a continent.
Functional Groups - Naming, Properties and Reactivities
A functional group is a group of atoms within a compound that is responsible for the characteristic chemical reactions of that compound. Functional groups also play an important part in organic compound nomenclature - combining the names of the functional groups with the names of the parent alkanes provides a way to distinguish compounds.
Some Common Functional Groups:
I. Alcohols
Alcohols are functional groups characterized by the presence of an -OH group. The general formula for alcohol is : R – OH where R is an alkyl . Compared to their parent alkanes, alcohols have higher boiling points. They are polar in nature caused by the difference in electronegativities between carbon and the oxygen atoms. In a reaction, alcohols cannot leave the molecule by themselves. To leave a molecule, they must be protonated to water. In the presence of a strong base, alcohols can be deprotonated.
Nomenclature of Alcohols
In naming alcohol, the terminal “-e” of the parent carbon chain (alkane, alkene, or alkyne) is dropped and the addition of “-ol” as the ending.
Example: CH3CH2- + OH CH3CH2-OH
ethyl + OH ethanol ( or ethyl alcohol )
Alcohols are used in beverages, antifreeze, antiseptics, and fuels. They are also used as preservatives for specimens in science, and they are used as reagents and solvents in industries because they can dissolve both polar and non-polar substances.
II. Ethers
Ethers are organic compounds that contain an ether group. An ether group is an oxygen atom connected to two alkyl or aryl groups. They follow the general formula R-O-R’ ( R is a substituent that can be the same or not ). The C-O-C linkage is characterized by bond angles of 104.5 degrees, with the C-O distances being about 140 pm. The oxygen of the ether is more electronegative than the carbons. Thus, the alpha hydrogens are more acidic than in regular hydrocarbon chains.
Ethers are nonpolar due to the presence of an alkyl group on either side of the central oxygen. The oxygen atom is unable to participate in hydrogen bonding due to the presence of alkyl groups on its side. Ethers have lower boiling points . However, as the alkyl chain of the ethers becomes longer, the difference in boiling points becomes smaller. This is due to the effect of increased Van der Waals interactions as the number of carbons increases, and therefore the number of electrons increases as well. The two lone pairs of electrons present on the oxygen atoms make it possible for ethers to form hydrogen bonds with water. Ethers are more polar than alkenes, but not as polar as esters, alcohols or amides of comparable structures.
Ethers have relatively low chemical reactivity. They resist undergoing hydrolysis. Ethers form peroxides in the presence of oxygen or air.
Nomenclature of Ethers
In naming , identify the alkyl groups on either side of the oxygen atom in alphabetical order, then write “ether.”
Examples: a) CH3 – O – CH2CH3 ethyl methyl ether
b) CH3 – O – CH3 dimethyl ether
Note: If the two alkyl groups are identical, the ether is called di[alkyl] ether.
III. Ketones
Ketone is an organic compound containing an oxygen atom joined to a carbon atom by a double bond. In ketone, the carbonyl functional group ( C=O ) is placed within a molecule. Its general structure is : O where R and R’ can be
R – C – R’
a variety of carbon-containing substituents.
Ketones are polar due to the carbonyl group and can interact with other compounds through hydrogen bonding. This hydrogen bonding makes ketones more soluble in water . Ketones are not hydrogen bond donors and they exhibit intermolecular attractions with other ketones. Because of this, ketones are often more volatile than alcohols and carboxylic acids of comparable molecular weights.
Nomenclature of Ketones
Naming of ketone is done by changing the suffix of the parent carbon molecule to “-one.” If the position of the ketone must be specified, parent chain is numbered by giving the lowest number to the carbonyl ( C=O ).
Example: CH2CH3
CH3 – C – C – CH3 3-ethyl-3-methyl -2- butanone
4 3 2 1
O
CH3
IV. Aldehydes
An aldehyde is an organic compound that contains a carbonyl group ( C=O ) with the central carbon bonded to a hydrogen and R group (R-CHO). In aldehydes, the carbonyl is placed at the end of the carbon skeleton rather than between two carbon atoms of the backbone ( just like in ketone ). Like ketones, aldehydes are sp2 hybridized.
Nomenclature of Aldehydes
Aldehydes are named by dropping the suffix “e” of the parent alkane, and adding the suffix “-al”.
Example: aldehyde with 2 C atoms
H
CH3C =O ethanal
Ketones and aldehydes can be readily reduced to alcohols in the presence of a strong reducing agent such as sodium borohydride. In the presence of strong oxidizing agents, they can be oxidized to carboxylic acids.
V. Carboxylic Acids
Carboxylic acids are organic acids that contain a carbon atom that participates in both a hydroxyl and a carbonyl functional group. Its general formula is : R-COOH.
A carboxyl group (COOH) is a functional group consisting of a carbonyl group (C=O) with a hydroxyl group (O-H) attached to the same carbon atom. Carboxyl groups have the formula O . It is usually written as – COOH. Carboxylic acids are
- C – OH
characterized by the presence of one carboxyl group. Since carboxylic acids contain both hydroxyl and carbonyl functional groups, they participate in hydrogen bonding as both hydrogen acceptors and hydrogen donors. Carboxylic acids increase stabilization of non-polar compounds and elevate their boiling points.
Nomenclature of Carboxylic Acids
For IUPAC nomenclature, the suffix “e” of the parent alkane is dropped and the suffix “-oic acid” is added.
O
Example: CH3 – C – OH ethanoic acid
Carboxylic acids are used as precursors to form other compounds such as esters, aldehydes, and ketones.
Carboxylic acids are used in the production of polymers, pharmaceuticals, solvents, and food additives. Carboxylic acids are generally produced from oxidation of aldehydes and hydrocarbons, and base catalyzed dehydrogenation of alcohols.
VI. Esters
Esters are functional groups produced from the condensation of an alcohol with a carboxylic acid. The general formula is: O
R – C – OR’
R and R’ are both alkyl groups. Esters are derivative of carboxylic acids where the hydroxyl (OH) group has been replaced by an alkoxy (O-R) group. They are commonly synthesized from the condensation of a carboxylic acid with an alcohol.
Esters are more polar than ethers, but less than alcohols. They participate in hydrogen bonds as hydrogen bond acceptors, but cannot act as hydrogen bond donors. Esters are more volatile than carboxylic acids of similar molecular weight.
Esters are everywhere. Most naturally occurring fats and oils are the fatty acid esters of glycerol. Esters are fragrant, and those with low molecular weights are commonly used as perfumes and are found in essential oils and pheromones. Polymerized esters, or polyesters, are important plastics.
Nomenclature of Esters
Ester names are derived from the parent alcohol and acid. For example, the ester formed by ethanol and ethanoic acid is known as ethyl ethanoate; “ethanol” is reduced to “ethyl,” while “ethanoic acid” is reduced to “ethanoate.”
O O
Illustration: CH3 – C – OH + CH3CH2 – OH CH3-CO-CH2CH3
ethanoic acid ethanol ethyl ethanoate
VII. Amines
Amines are compounds characterized by the presence of a nitrogen atom, a lone pair of electrons, and three substituents ( R ). The general formula for amines is N-R3. R can be H ( hydrogen ) or alkyl groups. Amines are basic compounds due to the lone pair of electrons. Amines have an unpleasant odor
Amine compounds can hydrogen bond, which affords them solubility in water and elevated boiling points. Amines are reactive due to their basicity as well as their nucleophilicity. Most primary amines are good ligands and react with metal ions to yield coordination complexes
Amines are starting materials for dyes and models for drug design. Amines are also used for gas treatment in the removal CO2 from combustion gases.
Nomenclature of Amines
In naming an amine compound, the prefix “amino-” or the suffix “-amine” is used.
For organic compound with multiple amino groups, the prefixes di, tri, tetr , etc. are used.
. .
Examples: a) CH3 – N – CH3 trimethylamine
CH3
. .
b) CH3CH2 – N – H ethanamine or ethyl amine
H
VIII. Amides
Amides are organic compounds containing nitrogen and has the general formula ; O
RC – NH2
The – NH2 group is directly attached to the carbonyl group ( C=O ).
Amide groups are found in nylon, silk, and wool. Amide is also present in insect repellant. Amides are used widely as color in crayons, pencils and inks, paper industry , plastic and rubber industry, and water and sewage treatment.
Nomenclature of Amide
In naming an amide compound, the suffix “e” of the parent alkane is replaced with the suffix “amide.
O
Example: CH3CH2CH2CH2C – NH2 pentanamide
IX. Alkyl halides
Alkyl halides are organic compounds containing halogens ( fluorine, chlorine, bromine or iodine ). Alkyl halide is formed by replacing one or more hydrogen atoms in an alkane with halogen atoms.They are also known as haloalkanes. Alkyl halides have the following general formula:
Primary alkyl halide : R – CH2 – X
Secondary alkyl halide: R – CH – R
X
R
Tertiary alkyl halide : R – C –R
X
where X is any halogen mentioned above.
Halogen imparts reactivity to alkyl halides. Alkanes impart odorlessness and colorlessness to alkyl halides. Some alkyl halides are less toxic and have high heat of vaporization. They are water-phobic ( they repel water) . Halogenated hydrocarbons are soluble in organic solvents. Some of the haloalkanes do not conduct electricity. Alkyl halides have higher boiling and melting point unlike alkanes. Haloalkanes are less flammable as compared to its component alkanes. Alkyl halides have stronger intermolecular forces (dipole-dipole interaction.)
Nomenclature of alkyl halides
In naming alkyl halides, the name of the alkyl residue is followed by the name of the halide. Examples are methyl iodide and ethyl chloride.
The IUPAC nomenclature considers an alkyl halide a substituted alkane . The name of the halogen is followed by the name of the alkane. Examples are iodomethane and chloromethane. . If an alkyl halide contains more than one halogen, the halogen names are noted in alphabetical order, such as 1-chloro-2-iodobutane.
Illustrations:
a) CH3 – Cl methyl chloride or chloromethane
b) CH3-CH2-F ethyl fluoride or fluoroehtane
c) CH3-CH-CH3 isopropyl iodide or 2-iodopropane
I
d) CH3-CH2-CH-CH3 sec-butyl bromide or 2-bromobutane
Br
e) CH3
H3C - C – CH3 tert-butyl bromide or 2-bromo-2-methylpropane
Br
Alkyl halides are used in labs as synthetic intermediate compounds. They are used as cleansers for cleaning. Commercial uses of haloalkanes include its use in fire extinguishers. Carbon tetrachloride is used to detect neutrinos.
A Survey Questionnaire on Brain Dominance and its Influence on Learning Styles
The Left-brain or Right-brain dominance or otherwise known as the Lateralization of the Brain Function makes the assumption that our approach to learning and thinking are different and based on which hemisphere of the brain ( left or right ) is superior or dominant over the other.
Also, based on this Brain Dominance Theory, each side of our brain ( left or right ) controls different types of thinking. Thus, each one of us may prefer one type of thinking and learning style over the other.
Homology and Analogy
The division is based on a distinction between similarity due to common ancestry, or homology, and resemblance which is due solely to similarity of function, called analogy. An example is the forelimbs of humans, horses, whales and birds which are judged homologous because
‘they are all constructed on the same pattern, and include similar bones in the same relative positions because these are all derived from the same ancestral bones. The wings of birds and insects, on the other hand, are analogous: they serve the same purpose, but do not constitute modified versions of a structure present in a common ancestor. The wings of birds and bats are homologous in skeletal structure because of descent from the forelimb of a common reptilian ancestor; but they are analogous in terms of their modification for flight—feathers in birds, skin membranes in bats.’
In other words, if a design similarity supports evolutionary assumptions, it is listed as an homology and is accepted as evidence for evolution. Conversely, if a design similarity does not support evolution, it is called analogy, and the conclusion is drawn that the similarity exists because a certain design is highly functional for a specific body part, and not because of a common ancestor. Many analogous structures are assumed to exist due to convergent evolution, which is defined as the separate evolution of similar structures because of similar environmental demands. Convergent evolution also is used to explain similar structures that have formed from different embryo structures or precursors.
Many examples of Homology are actually better explained by Analogy, and the resemblance that exists is often due to similarity of function and/or design constraints. The forelimbs of humans, whales and birds are similar because they serve similar functions and have similar design constraints. The conclusion that two homologous bones are similar because they are putatively ‘derived from the same ancestral bones’ (as Barr claims) is not based on direct evidence but instead on a priori conclusions demanded by macroevolution. Jones concluded that
“ … the evolutionist argument from homology lacks scientific content. This particular lack has very serious implications; it strikes at the root of all attempts by evolutionists to give homology an objective basis and distinguish homology (similarities due to descent) from analogy (similarities not due to descent). The only way they can recognize analogous variation, especially when due to convergent evolution is by criteria (e.g. genetic or embryological) which we now know do not hold for organs of "unquestionable" homology. The evolutionist concept of homology is now shown to be entirely subjective.”
Stephen J. Gould suggested that ‘the central task of evolutionary biology is … the separation of homologous from analogous likeness’, and then emphasized that ‘homology is similarity due to descent from a common ancestor, period’. The problem with this definition is that without direct knowledge we cannot know ancestry. In answer to the question ‘Can we identify fossil ancestors of species alive today?’, University of Michigan Professor Mark Siddall contends that this is impossible and that the use of stratigraphic data when assembling phylogenies must be based on speculation.
Huxley understood as far back as 1870 that when dealing with fossils, which are the only evidence we have of past life, one cannot distinguish uncles and nephews from fathers and sons. Among the many reasons ancestors cannot be distinguished from sister taxa, as noted by Siddall and others, is that there can be no positive evidence of ancestry, only inferences. Lack of evidence can only allow it as a possibility or an ad hoc postulate.
Although many similarities exist in almost all animal structures, structural variations are the norm. Often the variations found in the animal world seem to exist solely to produce variety, and not for the purpose of conferring a survival advantage. Some examples in humans are Attached earlobes, Tongue rolling, Hitchhiker’ thumb, Bent little finger, Interlacing fingers, Widow’ peak.
No biological or logical requirement exists to vary the design of bones, muscles and nerves needlessly in every living form beyond what is necessary to adapt the animal to its environment. Although variety is universal in the natural world, variety that interferes with the life process or an animal’ survival usually is avoided in animal design. Design constraints severely limit the possible variations in an animal’ anatomy, and excess deviation from the ideal can interfere with the animal’ ability to survive.
The many similarities that exist among members of the animal kingdom is the result of the fact that a single designer created the basic kinds of living ‘systems’, then specially modified each type of life to enable it to survive in its unique environmental niche. Examples of major environments for which organisms must be designed include the air, ground and water. Structures that serve similar purposes under similar conditions and that are nourished by similar foods ought to possess similarity in both design and function. This is illustrated in a critique of Berra’ Corvette analogy cited previously:
“ … Berra’ primary purpose is to show that living organisms are the result of naturalistic evolution rather than intelligent design. Structural similarities among automobiles, however, even similarities between older and newer models (which Berra calls "descent with modification") are due to construction according to pre-existing patterns, i.e., to design. Ironically, therefore, Berra’ analogy shows that even striking similarities are not sufficient to exclude design-based explanations. In order to demonstrate naturalistic evolution, it is necessary to show that the mechanism by which organisms are constructed (unlike the mechanism by which automobiles are constructed) does not involve design.”
History of Life on Earth Quiz 1
Human analysis and Level of assessment and solutions. After finishing lessons on Genetics and DNA, RNA, Protein synthesis, check out this this exercises.
Test your knowledge and understanding of the Geologic Time Scale and the Life forms that dominated and started during specific division. Measure your understanding on fossils, fossil types and ways of measuring the age of fossils.
History of Life on Earth Quiz 2 Read More......
Dating Fossils : Relative Dating and Absolute Dating
DATING FOSSILS
Knowing the age of a fossil can help a scientist establish its position in the geologic time scale and find its relationship with the other fossils.
Fossils, Fossil Types and Fosilization
There are two ways to measure the age of a fossil: relative dating and absolute dating.
1. RELATIVE DATING
I. Based upon the study of layer of rocks
II. Does not tell the exact age: only compare fossils as older or younger, depends on position in rock layer
III. Fossils in the uppermost rock layer/ strata are younger while those in lowermost deposition are oldest
How Relative Age is Determined
I. Law of Superposition: if a layer of rock is undisturbed, the fossils found on upper layers are younger than those found in lower layers of rocks
II. However, because the Earth is active, rocks move and may disturb the layer making this process not highly accurate
Rules of Relative Dating
A. LAW OF SUPERPOSITION:
Sedimentary layers are deposited in a specific time- youngest rocks on top, oldest rocks at the bottom
B. LAW OF ORIGINAL HORIZONTALITY: Deposition of rocks happen horizontally- tilting, folding or breaking happened recently
C. LAW OF CROSS-CUTTING RELATIONSHIPS: If an igneous intrusion or a fault cuts through existing rocks, the intrusion/fault is YOUNGER than the rock it cuts through
INDEX FOSSILS (guide fossils/ indicator fossils/ zone fossils): fossils from short-lived organisms that lived in many places; used to define and identify geologic periods
2. ABSOLUTE DATING
• Determines the actual age of the fossil
• Through radiometric dating, using radioactive isotopes carbon-14 and potassium-40
• Considers the half-life or the time it takes for half of the atoms of the radioactive element to decay
• The decay products of radioactive isotopes are stable atoms.
Carbon-14 Dating:
A living organism has carbon-14.
For the amount of Carbon in the organism’s body to become half, it will take about 5,700 years; which is the half-life of carbon-14.
Take a look at the table below. Then answer the exercise below.
Exercise Questions :
A.) Fill up the remaining data in the table.
4 , Mass Remaining : _____________ , Number of Years : __________
5 , Mass Remaining : _____________ , Number of Years : __________
6 , Mass Remaining : _____________ , Number of Years : __________
B.) What is the limit in using carbon-14 as a measure to determine a fossil’s age?
C.) Do you think Carbon Dating is an accurate method of determining the correct age of dead organisms? Please state your reason. Read More......
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