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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.