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).