Chemistry

Chemistry

1. Atoms elements and compounds

   • 100 different elements- periodic table
     • Colums- groups- similar properties
   • 1 element- 1 type of atom
     • Atoms represented- chemical symbols
       • Atoms have a tiny nucleus surrounded by electrons
     • When elements react, their atoms join
       • Compounds are formed when two or more elements combine
   • Atomic structure
     • Nucleus
       • Protons- positive
       • Neutrons- no charge
       • Electrons move around the nucleus when they are negatively charged
       • Atom has no overall charge
         • no of protons=no of electrons
     • Atomic number- proton number
       • =no of protons in nucleus
       • elements are arranged in order of their atomic number
     • Mass number
       • sum of protons and neutrons
   • Arrangement of electrons
     • Each electron in an atom is an energy level
       • Energy levels are represented as shells
         • Lowest energy level electrons- closer to nucleus
     • 1st shell-2 electrons 2nd shell-8 electrons 3rd shell-8 electrons
       • Electronic structure- Neon (10 electrons) 2.8
     • Elements in the same group
       • =same number of electrons in outer shell
     • Elements in same row
       • =same number of shells
     • Group 1 elements
       • Lithium, sodium, potassium
         • React quickly with water and oxygen
     • Group 0 elements
       • Stable arrangement of electrons
   • Forming bonds
     • different elements combined form compounds
     • Atoms combine they form molecules
       • Molecules- form elements or compounds
         • Same- elements
         • Different- compunds
     • Ionic bonding
       • metal- non metal
         • Ions formed- charged particles
         • Metals atoms lose electrons to form positively charged ions
         • Non- metal gain electrons to from negatively charged ions
     • Covalent bonding
       • Non metal- non metal
         • Share electrons
   • Chemical equations
     • Reactants to products
       • Mass is conserved so the mass of all the reactants must equal mass of all products
     • State symbols- s-solid g-gas l-liquid aq-aqueous (solution in water)

2. Limestone

   • Symbol eqaution
     • Calcium carbonate
       • CaCO3
     • Calcium Oxide
       • CaO
     • Carbon Dioxide
       • CO2
     • Water
       • H20
     • Calcium Hydroxide
       • Ca(OH)2
   • Calcium Carbonate- Calcium oxide+Carbon Dioxide
     • Thermal decomposition
       • Calcium oxide+Water= Calcium hydroxide
         • Dissolve Calcium Hydroxide- filtered to remove residue
           • Limewater
             • Calcium hydroxide+ Carbon dioxide- Calcium carbonate+ water
               • CaCO3- solid/ does not dissolve in water
                 • Limewater+Carbon Dioxide+ calcium carbonate+water
   • Rotary Kiln- calcium oxide is produced in a rotary kiln
   • Reactants of carbonates
     • Metal carbonates decompose when heated strongly enough
       • Metal carbonates- metal oxide+carbon dioxide
     • Carbonates react with acids
       • Carbonates+acid= salt, water and carbon dioxide
   • Cement
     • heating limestone with clay in a kiln
     • Mortor
       • Mixing cement and sand with water
       • Concrete
         • Mixing aggregate with cement, sand and water

3. Metals and their uses

   • Ore- a rock that contains a metal or metal compound to make it worth extracting the metal
   • The method used depends on its reactivity
     • Unreactive or native metals are found in the earth as a metal
       • Gold
     • If the oxides of metals are less reactive then carbon it can be reduced using carbon
     • Metals can be extracted using displacement using a more reactive element
   • Iron and steel
     • Iron is reduced in a blast furnace to make iron
       • 96% iron 4%carbon
         • Brittle- cast iron
     • Converted into alloys called steels
       • Low carbon steels
         • Easily shaped
           • iron and a little carbon
             • Cars
       • High Carbon steels
         • Hard
           • Iron and a lot of carbon
       • Stainless steels
         • Resistant to corrosion
           • Large quantities of other metals
             • Cutlery
       • Chromium nickel steels
         • Doesn't rust
           • Surgical instruments
   • Aluminium and Titanium
     • Resistant corrosion
     • Low densities
     • Extracted from oxides using carbon
     • Expensive-many stages/large amount of energy
     • Pure aluminium-not very strong Alloys- stronger and harder
   • Extracting Copper
     • Rich copper ores by smelting
       • Good conductor doesn't corrode good for wiring (pure) and plumbing
         • Copper can be purified by electrolysis
           • Extracting copper
             • Bioleaching
               • uses bateria to produce solutions using copper compounds
             • Phytomining
               • Uses plants to absorb copper compounds/ plants burned-ash from which copper can be extracted
           • Heating copper carbonate- copper carbonate-copper oxide+carbon dioxide
             • thermal decomposition
     • Coppers alloys
       • Brass
         • muscial instruments- alloy of copper and zinc
       • Bronze
         • Bronze age- alloy of copper and tin
   • Transition metals
     • Central block of periodic table
     • Propeties for building things
     • Good conductors of heat and electricity
     • High melting points
     • Good catalysts
     • Strong

4. Products from oil

   • Dark, smelly liquid
     • Mixture of lots of different chemical compounds
   • Separate the different boiling points know as fractions
     • Distillation
     • Compounds are mainly hydrocarbons
       • Only hydrogen and carbon
   • Fractional distillation
     • Separated into fractions- larger the molecule the higher the boiling point
     • Short chain
       • Lower boiling point more volatile(turns easily to gas) low viscosity(runny) flammable(burns easily useful as fuel
     • Long chain
       • Higher boiling point more volatile high viscosity(thick) not flammable (smokey flame)
     • The oil is vaporised
       • The vapours make the column cooler as they go up
         • Hydrocarbons condense when they reach their boiling points
           • Hydrocarbons with the smallest molecules have the lowest boiling boiling- collected at top
     • Burning fuels
       • lots of air-Produces carbon dioxide and water
       • Little air (incomplete combustion- carbon monoxide
         • Some particles my not burn- particulates
       • Fossil fuels contain sulfur compound- burnt- sulfur dioxide- acid rain
     • Alternative fuels
       • Biofuels-made from plants or animal products
         • Renewable burns better cheaper carbon neutral
         • Use of farmland destruction of habitat high temperature-sticky low temperature-freezes
   • Cracking hydrocarbons
     • Hydrocarbon can be broken down by heating them with steam to a very high temperature or by passing their vapours over a hot catalyst
     • Thermal decomposition reactions produce
       • Alkanes- CnH2n+2- saturated hydocarbons-useful for fuels
       • Alkenes- CnH2n unsaturated hydrocarbons double bonds more reactive
         • Polymers from alkenes
           • Plastics are made form polymers. Polymers are made from many small molecules joined together- monomers
             • Polymerisation
               • The double bond becomes single
                 • Smart polymers- hydrogels
   • Carbon Cycle
     • Combustion is upsetting the balance as it is releasing more CO2
       • Plants photosynthesis- CO2+H2O=O2+ glucose
       • Animals respire- o2+glucose=CO"+H2O
       • Burning fossil fuels+Deforestation
     • Nitrogen-78% Oxygen-21% CO"-0.04%
   • Earth Structure
     • Crust Mantle Outer core-liquid(hot) Inner core-liquid (pressure)
     • Tectonic Plates
       • Series of interlocking plates-semi liquid mantle-convection currents-radioactive processess
     • Earthquakes-snag Volcanoes-weakness Mountain-pressure
   • Plant oils
     • pressing+steam distillation
       • Heat water-steam The oils in lemon ring-vapourised condensed in condenser oil and water product
     • High in enegy-sun(photosynthesis)
     • Unsaturated-carbon double bond/ mono-monounsaturated oil have 1 carbon double bond
       • Saturated-do not have carbon double bonds-unsaturated fats will decolourise the bromine water
         • double bonds-liquid/chain bends/not packed as tight/easy to break/low melting and boiling points
       • Solid/tightly packed/hard to break/higher melting and boiling points
     • Hydrogenation-break carbon double bonds-hydrogen(nickel catalyst) molecules pack closely-solid at room temp
     • Cooking with veg oils-chemical reaction(permanent change)/ veg oil highr boiling point than water-cook higher temp/food cooks quicker
       • Nutrients-Vitimin E/high energy value/ high in unsaturated fats
       • Energy can turn to fat fats associated with heart disease
     • Emulsions-oil and water have been mixed
       • Hydro-water philic-love phobic-hates
       • Immiscible-do not mix miscible-do mix
     • Emulsifers-E numbers-keep oil and water from separating-ice cream