Why do alkali metals form ionic compounds?

Alkali metals form ionic compounds because they readily lose one electron to achieve a stable electron configuration.

Alkali metals, found in Group 1 of the periodic table, have one electron in their outermost energy level. This outer electron is relatively far from the nucleus and is not strongly attracted to it. Therefore, it is easily lost. When an alkali metal atom loses this electron, it forms a positive ion (a cation) and achieves a stable electron configuration, similar to that of a noble gas. This process is known as ionisation.

The electron that the alkali metal atom loses is often gained by a non-metal atom. Non-metals, particularly those in Group 7 of the periodic table, have seven electrons in their outermost energy level and need to gain one electron to achieve a stable electron configuration. When a non-metal atom gains an electron, it forms a negative ion (an anion). This process is known as electron gain or reduction.

The positive ion (cation) formed by the alkali metal and the negative ion (anion) formed by the non-metal are attracted to each other by strong electrostatic forces. This attraction between ions of opposite charge results in the formation of an ionic compound. Ionic compounds have high melting and boiling points due to these strong electrostatic forces, known as ionic bonds.

In summary, alkali metals form ionic compounds because they readily lose one electron to achieve a stable electron configuration. This electron is often gained by a non-metal atom, which forms a negative ion. The positive and negative ions are attracted to each other, resulting in the formation of an ionic compound.