Why are alkali metals highly reactive?

Alkali metals are highly reactive because they have one electron in their outermost shell which they readily lose to achieve stability.

Alkali metals, found in Group 1 of the Periodic Table, are known for their high reactivity. This is primarily due to their electronic configuration. They have one electron in their outermost shell, also known as the valence shell. This single electron is relatively far from the nucleus and is not strongly attracted to it, making it easier for the atom to lose this electron in a chemical reaction.

The loss of this electron results in the formation of a positive ion, or cation, which is a more stable state for the atom. This is because the atom achieves a full outer shell, similar to the configuration of the noble gases, which are known for their stability. This desire to achieve a stable electronic configuration drives the high reactivity of alkali metals.

Furthermore, as you move down the group, the reactivity of alkali metals increases. This is because the outermost electron is further from the nucleus and is less attracted to it, making it even easier to lose. For example, francium, at the bottom of the group, is more reactive than lithium, at the top.

In addition, alkali metals have low ionisation energies, meaning it requires less energy to remove the outermost electron. This also contributes to their high reactivity. For instance, when alkali metals come into contact with water, they react vigorously, producing hydrogen gas and alkaline solutions. This is a clear demonstration of their high reactivity.

In summary, the high reactivity of alkali metals is due to their electronic configuration, their desire to achieve a stable state, their increasing reactivity down the group, and their low ionisation energies.