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Alkali metals

The elements in group 1 are known as alkali metals. They react rapidly (very fast) with water, producing an alkaline solution and hydrogen gas. The metals become more reactive as you go down the group.

Halogens

The elements in group 7 are known as halogens. Fluorine and chlorine are gases. Bromine is one of only two liquid elements. Iodine is solid. They exist as diatomic molecules - they have two atoms in each molecule. As you go down the group the halogens become less reactive.

Noble gases

The elements in group 0 are known as noble gases. They are very unreactive and exist as individual atoms (monatomic).

Transition metals

The transition metals are elements which are found between groups 2 and 3. Well known examples are iron, copper and gold. They are generally quite dense (heavy) and many form brightly coloured compounds.