Chemistry Unit 1

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Basic Chemistry

Neutrons and Protons in the nucleus. Electrons in shells orbiting.

Neutrons (neutral charge), Protons (positive), Electrons (negative).

All elements want a full outer shell (unreactive).

Bonds are ionic (giving/ borrowing of electrons) or covalent (sharing of electrons).

Atomic number= no. of electrons= no. of protons

Mass number= no. of neutrons+ protons so no. of neutrons= mass number- atomic number.

2 electrons in first shell, 8 in second, 8 in third. Electronic structure is coordinated from this.

Mass must always be conserved before and after a reactions so we balanced equations:

2Mg+O2= 2MgO

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Limestone

Limestone-- Calcium Oxide + Carbon Dioxide (Thermal Decomposition)

Calcium Oxide + Water-- Calcium Hydroxide

Calcium Hydroxide + Carbon Dioxide-- Limestone + Water

Limestone + Sulfuric Acid-- Calcium Sulfate + Carbon Dioxide + Water

Limestone + Hydrochloric Acid-- Calcium Chloride + Carbon Dioxide + Water

Powdered Limestone + Clay-- Cement

Cement + Sand + Water-- Mortar (+ Calcium Hydroxide)

Cement + Sand + Aggregate (Water and Gravel)-- Concrete

Advantages: Builds houses and roads, can make dyes and paints, neutralise acidic soil, neutralise sulfur dioxide, leads to employment.

Disadvantages: requires fossil fuels (CO2 emissions), creates problems in the physical landscape, produces unsightly tips and causes breathing problems.

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Metal Extraction

An ore is a rock without enough metal for extraction.

Reduction (if below carbon), Electrolysis (if above).

Reduction produces less pure results than Electrolysis.

An electrolyte conducts the electricity (free ions). Electrons are taken away at the anode and given away at the cathode creating attraction. Pure atoms will bond to the cathode.

Diplacement reactions can be used with scrap iron (much cheaper and more reactive).

Bioleaching is using bacteria to consume the bond between copper and sulphur. The leachate can be filtered for copper.

Phytomining is planting plants in copper rich soils. They can't use the copper so just absorb it and it builds up. The harvest can be dried and burnt leaving copper in the ash from the furnace- carbon neutral emission.

Recycling uses less energy, produces less CO2 and conserves metal and fossil fuel resources. It also creates employment.

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Properties of Metals and Alloys

Most are conductive, strong but can be bent and are malleable.

Hoever, some corrode over time.

Low density metals are often useful in drinks cans and aeroplanes.

Plumbing pipes have to be below hydrogen in the reactivity series otherwise it may react with water.

Alloys can make metals better at a function.

e.g pure iron is too bendy as its atoms are all the same size.

Cast iron, however, has 4% carbon impurities so is more brittle.

Other examples are Stainless Steel (Iron + Chromium and sometimes Nickel), corrosion resistant.

High carbon steel is very hard so used for bridges and cutting tools,

Beonze is Copper and Tin- harder than Copper so used for medals and statues.

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Crude Oil

Crude Oil is a mixture of many different hydrocarbons which have different boiling points and melting points.

Lower down it is hotter where the longer hydrocarbons are tapped off.

Crude oil is mainly alkanes. Organic family. Saturated bonds. Cn H2n+2

Shorter molecules have lower viscosities, higher volatilities, higher flammability.

Really thick viscosities like bitumen are used for roads and lubricating engine parts.

Cracking- Thermal Decompositon

Longer Alkane vaporised over a hot catalyst at a temperature of 400- 700 degrees celsius.

Produces an alkene and 1+ alkane. 

Alkenes are unsaturated (colourless bromine water) and can be used to make polymers. They're treated as monomers and their double bonds seperate outwards with one another.

Polymers are used for plastic bags, lycra, bouncy balls, dental treatments.


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Environmental Problems with Crude Oil

Oil spills can kill wildlife and pollute vast areas of marine life.

Oil is a non renewable resource that cannot develop at the same rate as our demand.

Particulates cause global dimming which blocks out sunlight.

Sulphur dioxide causes acid rain which will slowly destroy all life on Earth if in high enough concentrations.

Carbon Monoxide is poisonous and can kill if in high enough concentrations.

Carbon dioxide causes global warming which melts ice caps contributing to higher sea levels and eventualy flooding in low lying areas.

Nitrous Oxides can also be produced if burnt at a high enough temperature, these can cause asthma and other health issues. 

Reducing Sulphur dioxide: taking away impurities, not burning crude oil and neutralising the acidity.

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Ethanol and Oils

Ethene + Steam-- Ethanol (high temperature, uses crude oil, could become expensive)

Sugar-- Ethanol + Carbon Dioxide (lower temperature, requires further purification, simple equipment)

Vegetable Oils have higher boiling points than water so are often used in cooking.

Also increases the energy we get from food.

Vegetable Oils are unsaturated and animal fats tend to be saturated.

Hydrogenation increases the melting point, 60 degrees, nickel catalyst.

Monounsaturated fats only have one double bond, polyunsaturated fats have more than one.

Partially hydrogenated oils have trans fats which could be quite bad for you.

Hydrophilic head is attracted to water.Hydrophobic tail is repelled by water.

Emulsifier molecules encourage suspension of liquids.

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Tectonics and Life on Earth

Wegner was right because of similar fossils and also jigsaw continets.

He used bad calculations and was disreputed because he had a PhD in astronomy not geology.

The plates move because of convection currents caused by radioactive decay.

Earthquakes and Volcanoes are hard to predictg because the mini earthquakes can be false alarms as they are sudden jolts.

Oceans and green plants absorbed the CO2 in the early atmosphere.

The ozone layer allowed for complelxity of species.

The primordial soup suggests a reaction with nitrogen, hydrogen, ammonia and methane caused the creation of amino acids- the building blocks of life.

Air can be fractionally distilled.

Dust is filtered, air is cooled, CO2 is removed and then they are warmed slowly up.

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