Chemistry Complete Revision Core-IGCSE/CIE

1-Particulate Nature of Matter

• Solids- fixed vo
• lume, vibrate about a fixed point, strong intermolecular attractions.
• Liquids- Weaker attractive forces, Take the volume of the container, slide.
• Gases- almost no intermolecular forces, move around quickly, collide frequently.
• Interconversions- Condensation/Freezing(solidifacation)- particles lose KE so when collide they cannot bounce again, so take up a more fixed point. Evaporation,Boiling- Gain KE so particles move more quickly, lose their fixed shape.
• Diffusion- the spreading out of particles from an area of high concentration to an area of low concentration- affected by lighter/heavier particles, higher temperature particles diffuse faster.
• Evidence for diffusion-in gases spread across- bromine gas. Liquids- liquids and solutions travel up the liquids.

2- Experimental Techniques

• Time- Stopwatch/Clock
• Mass-Balance
• Temperature-Thermometer
• Volume-Measuring cylinder, beaker, Burette, Pipette,Gas syringe
• Purity- Chromatography with use of solvent, penciled line, coloured substance- a dot of the coloured substance is placed on a pencilled line with the solvent level below the line. The ink would gradually spread out creating different coloured inks on the paper that can be compared to other substances to see if a substance is pure or contains other substances. You could also check the boiling/melting point of a substance to compare to those with set bp/mp , if there is a bigger change it means there are more impurities. This is very important in foodstuffs/drugs to check if they are pure and safe to use.
• Other purification techniques-Filtration (to separate an insoluble solid from a luquid), Crystallisation( to separate a soluble solid from a liquid with different bp), Simple Distillation( to separate liquids that have significantly different bp) and Fractional Distillation( liquids that have close range bp)-Fractional column- separating petroleum.

3-Atoms/Elements/Compounds

• Proton- (+1), mass of 1
• Neutron- (0) mass of 1
• Electron -(-1) mass of 1/1840
• Proton number- number of protons present in the nucleus of an elemnt, Nucleon number-number of protons and electrons present in a nucleus of an atom.
• Isotopes-same amount of protons and electrons, different amount of neutrons - non-radioactive/radioactive, radioactive isotopes used in medicine to sterilise medical eqeuipment,radiotherapy and industrial in to detect leaks by adding to oil/natural gas and using GM tube to check.

4-Stoichiometry

• Relative atomic mass- mass of the element (average) for example 12 for Carbon
• Relative molecular mass- adding up of relative atomic mass.
• Mole concept- 6x10(23) , formulas include -Moles=Mass/RMM   Concentration=Moles/Volume 

5-Electricity and Chemistry

• Electrolysis of Molten Lead Bromide - cathode- lead, anode- bromine gas
• Electrolysis of Concentrated HCl- cathode-hydrogen, anode-chlorine
• Electrolysis of Concentrated NaCl- cathode-hydrogen, anode-Chlorine
• Usually metals and hydrogen are made at the cathode, non-metals are made at the anode.With a molten compound (iron oxide) you will just get iron and oxygen gas. In a solution, the less reactive of the two substances will produce hydrogen not sodium.
• Electroplating-anode has to be made out of the metal you want to electroplate the object with-ions of the same metal as the electrolyte, cathode with the object you want to electroplate.(do not corrode/rust/look prettier)
• Aluminium/copper used for cables-good conductors of heat and electricity/ductile, they are…