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Science

Groups in the periodic table

The alkali metals, halogens and noble gases are three important groups in the periodic table.

The alkali metals are soft, reactive metals. They react vigorously with water and become more reactive as you go down the group.

The halogens are reactive non-metals. They become darker as you go down the group. Their reactivity decreases as you go down the group and their boiling points increase. A more reactive halogen will displace a less reactive halogen from solutions of its salts.

The noble gases are unreactive non-metals, which exist as single atoms.

The alkali metals - overview

The elements in group 1 are called the alkali metals. They belong to the left-hand column in the periodic table. They are very reactive and must be stored in oil to avoid contact with air or water.

alkali metals: Li, Na, K, Rb, Cs, Fr

The alkali metals - Group 1

Common properties

The alkali metals have the following properties in common:

  • they have low melting and boiling points compared to most other metals
  • they are very soft and can be cut easily with a knife
  • they have low densities (lithium, sodium and potassium will float on water)
  • they react quickly with water, producing hydroxides and hydrogen gas
  • their hydroxides and oxides dissolve in water to form alkaline solutions

Back to Patterns in properties index

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