A group (also known as a family) is a vertical column in the periodic table of elements.
The alkali metals – Group I
- Very reactive soft metals.
- Increases in reactivity down the group.
- They have low densities.
- They react quickly with oxygen in air and with water.
Alkali metals are stored in oil to prevent reactions with water and with oxygen.
The alkaline earth elements – Group II
- They are all reactive elements.
- Reactivity increases down the group.
The halogens – Group VII
- These are very reactive non-metals.
- Reactivity decreases down the group.
- They have low melting and boiling points.
- They react with hydrogen to form compounds that dissolve in water to form acidic solutions. (Eg. Hydrogen chloride gas dissolves in water to form hydrochloric acid solution.)
- They react vigorously with sodium and the other alkali metals.
The noble gases – Group 0
- They are all gasses at room temperature.
- Going down the group, the boiling point and the density increases.
- They are least reactive of all elements.
s-block and p-block elements
The elements in Groups I and II form the s-block elements. They have lower densities, melting points and boiling points than most other metals. They are more reactive than the d-block metals.
The elements in Groups III, IV, V, VI, VII and 0 are called the p-block elements. They are mainly non-metals but some of these in Group IV are metals (eg. tin and lead).