C1 Revision

Atomic structure

• Atoms consist of a central nucleus which contains protons and neutrons

• The nucleus is surrounded by shells of electrons

Electron Structure

• The atomic number of an element gives the number of electrons

• The max number of electrons in each shell is 2,8,8

Electrons and the periodic table

• Groups = the columns (up and down) the table

• Periods = the rows (going across) the table

• Number of electrons in outer shell = group number

• Number of shells = period number

Mendeleev

• Developed the modern Periodic table

• Arranged the elements in order of their atomic mass

• Left gaps for undiscovered elements

• Predicted properties for elements in gaps

• When discovered, properties of the new elements matched the predictions

Group 1 reactions

• Group 1 – lithium, sodium, potassium• Group 1 react with oxygen to form oxides• Eg. Lithium + oxygen Lithium oxide

• Group 1 react with water to form hydroxides and hydrogen gas

• Eg. Sodium + water Sodium hydroxide + hydrogen

• Reactivity of group 1 increases going down the group

Group 7 displacement reactions

• Group 7 reactivity decreases down the group

• A more reactive halogen can displace a less reactive halogen from a compound

• Chlorine + sodium bromide Bromine + Sodium chloride

Flame tests and silver nitrate tests

• Flame tests can be used to identify sodium or potassium in a compound

• Sodium – orange yellow flame• Potassium – lilac flame

• Silver nitrate can be used to identify chloride or iodide in a compound

• Chloride – white precipitate• Iodide – yellow precipitate

Chemical formulae

• Each element in a formula has a capital letter

• The number of atoms is written after the symbol

Combining ions

• To work out a formula from the table of ions,

• Write down the positive and negative ions

• “Swap and drop” the numbers

• eg. Al3+ and Cl- becomes AlCl3

Acid reactions

• Acids react with metals to form a salt and hydrogen

• Eg. Magnesium reacts with sulphuric acid to form magnesium sulphate (salt) and hydrogen

Acid reactions

• Acids react with metal oxides to form salt and water

• Eg. Copper oxide reacts with sulphuric acid to form copper sulphate (salt) and water

Acid reactions

• An alkali is a metal hydroxide

• Acids react with alkalis to form a salt and water

• eg. Sodium hydroxide reacts with hydrochloric acid to form sodium chloride (salt) and water

Acid reactions

• Acids react with metal carbonates to form a salt, carbon dioxide and water

• Eg. Calcium carbonate reacts with sulphuric acid to make calcium sulphate, carbon dioxide and water

Signs of a chemical change

• Colour change

• Precipitate

• Temperature change

• Produces a gas

Exothermic and Endothermic

• An exothermic reaction is a reaction which gives out heat

• An endothermic reaction is a reaction which takes in heat

Rates of reaction

• Factors which affect rate of reaction are:– Temperature (higher temperature increases

rate)– Concentration (more concentrated acids

react faster)– Surface area (crushing up solid into a powder

makes it react faster)– Adding a catalyst (a substance added to the

reaction to make it faster)

Nanoscience

• A nanometre is 1 thousand millionth of a metre • A nanoparticle is a particle that has a size in

the range 1 to 100nm• Nanoparticles have new and different

properties to the same material in bulk form• Eg. Nanosilver which is antibacterial and is

used in sterilising sprays in hospitals and self cleaning fridges

• Some people concerned – may pass through the skin as so small. Long term effects on health not known.

Crude oil

• Mixture of hydrocarbons

• Hydrocarbon = compound of carbon and hydrogen only

• Each fraction in crude oil has a different boiling point

• Larger molecules – higher the boiling point

• Separated by fractional distillation

Fractional distillation

• Crude oil is heated and enters fractionating column

• Vapours cool down as they rise up the column

• High boiling point fractions (large molecules) condense at the bottom of the column

• Low boiling point fractions (small molecules) condense at the top of the column

Fuels

• Hydrocarbons can be burned to produce energy (react with oxygen) - combustion

• Products are carbon dioxide and water

• Carbon dioxide contributes to global warming – greenhouse gas

• Some fuels contain sulphur as an impurity

• Sulphur burns to make sulphur dioxide which contributes to acid rain

Atmosphere

• Early atmosphere came from volcanoes• Atmosphere has changed over geological time (millions

of years)• Evolution of life has had a massive impact on the

atmosphere• Plants – photosynthesis – use up carbon dioxide and

make oxygen• All living things – respiration – use up oxygen and

produce carbon dioxide• Combustion of fuels – uses up oxygen and produces

carbon dioxide• All three processes keep the levels of oxygen and

carbon dioxide the same

Global warming

• Increase in CO2 due to burning hydrocarbon fuels

• Earth radiates heat which is then trapped by the atmosphere, the more CO2 there is the more heat is trapped

• Greenhouse effect

Continental drift

• Alfred Wegener – theory of continental drift

• Continents were once joined and have split up and moved apart

• Evidence – closely fitting coastlines, matching fossils and rocks in different continents

• Why not accepted in Wegener’s time? He couldn’t explain how continents move

Plate tectonics

• Explains Wegeners theory• Earth’s crust is broken up into pieces called

tectonic plates• Plates are moving – this is how continents have

moved apart• Some plates move apart – magma rises to fill

the gap forming new igneous rock• Plates move together, one plate sinks beneath

the other and melts to form magma• Earthquakes and volcanoes occur on plate

boundaries