SPM Chemistry

Chemical Properties of Group 1 Elements

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Chemical Properties of Alkali Metals


  1. Group 1 metals are very reactive metals.
  2. They all show the same chemical properties.
  3. They can react with water and non-metal such as oxygen and chlorine to form a new compound.
  4. The table to the right shows the electron arrangement of all the Group 1 metals. All the atoms of Group 1 metal consist of 1 valence electron.
  5. When an alkali metal atoms react, it loses the valence electron to form a positively charged ion.
    Example:
    Li →Li+ + e
    Na →Na+ + e
    K → K+ + e
  6. They tend to react mainly with non-metals to form ionic compounds.

Safety Precaution

  1. Alkali metals are very reactive.
  2. Therefore it must be kept in paraffin oil to prevent them from reacting with oxygen and water vapour in the air.
  3. We must avoid to hold group 1 metals with bare hand because they may react with water on our hand.
  4. We must wear safety goggles and gloves during handling experiment involving group 1 metal.

Explaining the Reactivity Trend of the Alkali Metals

  1. When an alkali metal atom reacts, it loses its valence electron to form a positively charged ion.
    Example
    Li → Li+ + e
    Na → Na+ + e
    K → K+ + e
  2. As we go down the group from one element down to the next, the atomic radius gets bigger due to an extra filled electron shell.
  3. The valence electron is further and further from the nucleus. Thus the attraction force between the nucleus and the valence electron become weaker and weaker.
  4. This causes the valence electron is easier to be released to form an ion when the atom takes part in a reaction.