2.1.2 Compounds, formulae and equations
Definitions
| Term | Definition |
|---|---|
| Binary compounds | Compounds that contain two elements only. |
| Diatomic molecules | Molecules composed of two atoms only. |
| Polyatomic ions | Ions containing more than one atom. |
Concepts
Anions to know
| Ion | Formula |
|---|---|
| Nitrate | \(NO_3^-\) |
| Carbonate | \(CO_3^{2-}\) |
| Sulfate | \(SO_4^{2-}\) |
| Hydroxide | \(OH^-\) |
Cations to know
| Ion | Formula |
|---|---|
| Ammonium | \(NH_4^+\) |
| Zinc ion | \(Zn^{2+}\) |
| Silver ion | \(Ag^+\) |
Writing ionic equations
- We can only dissociate aqueous compounds
- Split all chemicals into ions
- Cancel out spectator ions
- Note: No aqueous compound = no ionic equation
Solubility
| Solubility | Compounds |
|---|---|
| Soluble in water | - All common sodium, potassium and ammonium salts (also their carbonate and hydroxide salt) - All nitrates - Most common chlorides - Most common sulfates |
| Insoluble in water | - Silver chloride, lead chloride - Lead sulfate, barium sulfate, calcium sulfate, strontium sulfate - Most common carbonates - Most common hydroxides |