Alkali Metals

• Alkali metals are metals in group 1 of the periodic table.
• Alkali metals have one electron in their outer shell, so they have similar chemical properties.
• They are reactive metals.

Reactions with Water

Alkali metals react with water to produce alkaline metal hydroxide and hydrogen gas.

For example, in the reaction between sodium and water,

2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)

Reaction becomes more vigorous as you go down the group 👇:

For IGCSE Chemistry, you should be able to explain the trend of reactivity of alkali metals 

Explanation of the Trend

• The number of electron shells increases as you go down the group. 
  • For example, lithium has two electron shells, sodium has three electron shells and potassium has four electron shells.
• Outer shell of alkali metals has only one electron each. 
• When alkali metals react, they lose the electron to get a full outer electron shell.
• With more number of electron shells, the electrostatic attraction between the positively charged nucleus and the negatively charged outer electron is weaker.
• It is easier to lose the electron at the outer shell as you go down the group.
• Therefore, the reactivity of alkali metals increases as you go down the group.

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