What are the chemical properties of alkali metals?

Alkali metals are highly reactive, have one electron in their outer shell, and form alkaline solutions when dissolved in water.

Alkali metals, found in Group 1 of the Periodic Table, are known for their high reactivity. This is due to the single electron in their outermost shell, which they are eager to lose in order to achieve a stable electron configuration. This makes them excellent reducing agents. The reactivity of alkali metals increases down the group, meaning that Francium is the most reactive and Lithium is the least.

When alkali metals come into contact with water, they react vigorously, producing hydrogen gas and forming hydroxides. These hydroxides are alkaline, hence the name 'alkali metals'. This reaction also releases a significant amount of heat, often enough to ignite the hydrogen gas produced. For example, the reaction of sodium with water can be represented as: 2Na(s) + 2H2O(l) -> 2NaOH(aq) + H2(g).

Alkali metals also react with oxygen in the air. They form oxides, peroxides, or superoxides depending on the specific metal and its reactivity. For instance, lithium forms lithium oxide (Li2O), while sodium forms sodium peroxide (Na2O2), and potassium, rubidium, and caesium form superoxides (KO2, RbO2, CsO2 respectively).

In terms of physical properties, alkali metals are soft and have low melting and boiling points compared to most other metals. They are also good conductors of heat and electricity. These properties, combined with their high reactivity, mean that alkali metals have to be stored under oil to prevent them from reacting with moisture or oxygen in the air.

In summary, the chemical properties of alkali metals - their high reactivity, tendency to form alkaline solutions, and ability to act as reducing agents - are all due to their electron configuration.