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
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)
Na+ (aq) + Cl- (aq) + Ag+ (aq) + NO3- (aq)→ AgCl (s) + Na+ (aq) + NO3- (aq)
Net ionic equation:
Cl- (aq) + Ag+ (aq) → AgCl (s)