GCSE Combined Science (AQA)

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Group 1: Alkali Metals

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Atomic structure and the periodic table The periodic table

Group 1: Alkali Metals

6:12 Properties of Group 0 and 1 elements
Spec 4.1.2.5 4.1.2.1
Previous Group 0: Noble Gases Next Group 1: Reaction with Water
  • Group one elements are metals found in the first column of the periodic table, known as alkali metals.
  • These elements are very reactive and react with water, oxygen, and group seven elements.
  • Reactions involving group one elements can be dangerous and require caution.
  • Cesium reacting with water can produce a violent explosion.
  • Group one elements have one electron in their outer shell, which gives them characteristic properties.
  • Lithium, sodium, and potassium are the first three members of group one, with 3, 11, and 19 electrons respectively.
  • These elements react by losing their single outer electron, forming a positive ion with a plus one charge.
  • Reactivity increases down the group, with lithium being the least reactive and francium the most reactive.
  • Atoms increase in size down the group, making the outer electron further from the nucleus and less attracted, thus more easily lost.
  • Alkaline metals are soft, can be cut with a knife, have low density, and float on water.
  • They have relatively low melting and boiling points compared to other metals.
  • Group one metals have melting points below other metals, with sodium and potassium having melting points below 100 degrees Celsius.
  • Melting points decrease down the group, and trends can be used to predict properties of other group one metals.
  • Predictions of properties, such as melting points, can be made based on trends, with a range of acceptable answers in exams.

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