A-LEVEL NOTES
  • Home
  • Biology
    • AQA
    • OCR
  • Chemistry
    • AQA
    • OCR
  • Home
  • Biology
    • AQA
    • OCR
  • Chemistry
    • AQA
    • OCR
A-LEVEL NOTES

A-LEVEL OCR ChEMISTRY NOTES 
Compounds, formulae and equations


Picture
DOWNLOAD PDF
Made with ❤️by snaprevise.co.uk

Ionic Compounds
  • An ion is an atom or molecule with a net charge formed through the gain or loss of electrons
  • A cation is formed from the loss of electrons
  • An anion is formed from the gain of electrons
  • Ionic compounds are composed of oppositely charged ions. The overall charge is zero as the ionic charges balance.
  • e.g. write the formula of sodium carbonate
We need 2 x Na+ to balance the -2 charge of CO3^2-
The formula is Na2CO3​

Balanced Equations

  • When a chemical reaction occurs, no atoms are created or destroyed. The atoms in the reactants rearrange to form the products.
  • In a balanced equation, there is the same number of atoms of each element in both the reactants and products.
  • State symbols are written after every species to indicate the physical state
    • Solid (s)
    • Liquid (l)
    • Gaseous (g)
    • Aqueous (aq) - dissolved in water
  • Ionic equations can be written for any reaction involving ions in solution, where only the reacting ions and the products they form are included.
  • The net ionic equation shows only the ions directly involved in the reaction (removing spectator ions). e.g. 
NaCl (aq) + AgNO3 (aq) → AgCl (s) + NaNO3 (aq)
Na+ (aq) + Cl- (aq) + Ag+ (aq) + NO3- (aq)→ AgCl (s) + Na+ (aq) + NO3- (aq)

Net ionic equation:
Cl- (aq) + Ag+ (aq) → AgCl (s)

A-LEVEL BIOLoGY

A-level AQA Biology
A-level OCR Biology
A-level Edexcel Biology

A-LEVEL CHEMISTRY

A-level AQA Chemistry
A-level OCR Chemistry
​A-level Edexcel Chemistry