Chemical Properties of Alkali Metals
- Group 1 metals are very reactive metals.
- They all show the same chemical properties.
- They can react with water and non-metal such as oxygen and chlorine to form a new compound.
- 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.
- When an alkali metal atoms react, it loses the valence electron to form a positively charged ion.
Li →Li+ + e
Na →Na+ + e
K → K+ + e
- They tend to react mainly with non-metals to form ionic compounds.
- Alkali metals are very reactive.
- Therefore it must be kept in paraffin oil to prevent them from reacting with oxygen and water vapour in the air.
- We must avoid to hold group 1 metals with bare hand because they may react with water on our hand.
- We must wear safety goggles and gloves during handling experiment involving group 1 metal.
Explaining the Reactivity Trend of the Alkali Metals
- When an alkali metal atom reacts, it loses its valence electron to form a positively charged ion.
Li → Li+ + e
Na → Na+ + e
K → K+ + e
- 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.
- 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.
- This causes the valence electron is easier to be released to form an ion when the atom takes part in a reaction.