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Science

Alkali metals

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The Group 1 elements in the Periodic Table are known as the alkali metals. They include lithium, sodium and potassium, which all react vigorously with air and water.

The reactivity of the alkali metals increases down the group. Flame tests are used to identify alkali metal ions in compounds.

Alkali metals

Diagram showing group 1 of the periodic table

Group 1 of the periodic table

The Group 1 elements, which include lithium (Li), sodium (Na) and potassium (K) are also known as the alkali metals. They all have one electron in the outer shell and so they have similar properties.

Reaction with air and water

Potassium reacting with water

Potassium reacts with a lilac flame

Lithium, sodium and potassium all react vigorously with water. Hydrogen gas bubbles off and, in the case of potassium, this burns with a lilac flame. The metal hydroxide is formed which is a strong alkali.

Alkali metals need to be stored under oil to prevent them reacting with the oxygen and water vapour in the air.

The reactivity of the alkali metals increases down the group. Potassium reacts more vigorously than sodium and lithium is the least reactive.

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