AQA CHEMISTRY PAPER 1 (Higher Tier, Triple Science) - KEY POINTS FOR GCSE 2018
(Forgot to specify tier etc on the last post, sorry!)
So like I did for Biology Paper 1, here’s a list of things for Chemistry Paper 1 which I find a good idea to remember/tend to forget! I hope it’s useful!
How Fuel Cells work:
Moles = mass/Mr
Avogadro’s constant = 6.02 x 10^23
1 dm3 = 1000 cm3
Concentration in mol/dm3 = moles/volume
Concentration in g/dm3 = mass/volume
Remember to convert volume in cm3 to dm3 (divide by 1000!!) if it’s given in cm3
Moles of a gas = volume (dm3)/24
Periodic table development went: tiny spheres arranged by atomic weights (Dalton), triads where middle element was avg. mass (Dobereiner), period similarities noticed but ignored due to lack of symbols, law of octaves but left no space for discoveries (Newlands), elements placed by mass and properties with spaces (Mendeleev), order of atomic numbers after discovery of nucleus (Moseley)
The size of an atom is approximately 1 x 10^-10
The size of the nucleus is approximately 1 x 10^-14
If percentage yield is more than 100%, there may have been a greater mass of the reactant, or the sample was not dry
If the percentage yield is less than 100%, it may be because the reaction was incomplete, other unexpected reactions took place, or some of the product was lost
History of the atom goes as: Thomson discovered electrons so developed plum pudding model, Geiger & Marsden’s experiment showed a nucleus (because some of the alpha particles were deflected rather than going straight through meaning mass was concentrated in the centre) which had a positive charge, Bohr’s experiments showed electrons orbited at a distance or they would spiral inwards, Chadwick provided evidence of neutrons, later experiments then showed the positive charge could be split up into protons
Metallic bonding is a lattice is positive ions held by electrostatic attraction to negative delocalised electrons
Ionic bonding is strong electrostatic forces of attraction between non-metal negative ion and metal positive ion
Conduct when liquid as ions are not fixed and can therefore move around
Simple covalent structures have weak intermolecular forces between individual molecules
Fullerenes are good lubricants because they are round and therefore roll
Course particles are between 1 x 10^-5 m and 2.5 x 10^-6 m
Fine particles are between 1 x 10^-6 m and 2.5 x 10^-7 m
One nanometre is 0.000000001 (billionth) of a metre as is written as 1 x 10^-9 m
Nanoparticles have a diameter between 1nm and 100nm
Boiling points of noble gases increase as you go down the group
Alkali metals have lower melting/boiling points, are softer, less dense, and are weaker than transition metals
A more reactive halogen will displace a less reactive halogen from a solution of its salt
This is the reactivity series:
A more reactive metal will displace a less reactive metal from a solution of its salt
The easier it is for a metal to lose an electron, the more reactive it is
In the electrolysis of a molten compound, metals go form at the cathode and non-metals form/are released at the anode
In the electrolysis of an aqueous solution, hydrogen is released from the cathode if the metal is MORE reactive than it, and oxygen is released from the anode UNLESS the solution contains halide ions (in which case the halide ions are released as halogens)
For bonds to be broken, reacting particles must collide with sufficient energy
This is what Energy profile diagrams look like (remember the products of an exothermic reaction will have LESS energy):
Overall energy change = bonds broken - bonds made
A negative energy change is exothermic because the products had MORE energy, as it was released
Bases are insoluble alkalis and can include metal carbonates, metal oxides, and metal hydroxides
Filtration is used to separate a soluble solid from an insoluble solid
Crystallisation is used to obtain a soluble solid from a solution
Simple distillation is used to obtain a solvent from a solution
Fractional distillation is used to separate mixtures in which the components have different boiling points
Chromatography is used to separate the different soluble, coloured compounds in a mixture
GOOD LUCK ON YOUR EXAM TOMORROW EVERYONE!! Get plenty of sleep, especially since it’s an AM exam!
