Why do alkali metals form strongly alkaline solutions?

Alkali metals form strongly alkaline solutions because they react vigorously with water to produce hydroxide ions (OH-).

Alkali metals, which include lithium, sodium, potassium, rubidium, caesium, and francium, are located in Group 1 of the periodic table. They are characterised by their single electron in the outermost energy level, which they are eager to lose in order to achieve a stable electron configuration. This makes them highly reactive, especially with water.

When an alkali metal comes into contact with water, a displacement reaction occurs. The metal donates its outer electron to a water molecule, resulting in the formation of a metal hydroxide and hydrogen gas. The equation for this reaction is: 2M(s) + 2H2O(l) → 2MOH(aq) + H2(g), where M represents an alkali metal. The metal hydroxide (MOH) that is formed is a strong base, meaning it readily dissociates in water to produce hydroxide ions (OH-).

The presence of these hydroxide ions is what gives the solution its alkaline properties. In chemistry, an alkaline solution is one that has a pH greater than 7, which is the neutral point on the pH scale. The more hydroxide ions there are in a solution, the higher its pH will be, and therefore the more alkaline it is.

So, when alkali metals react with water, they produce a large number of hydroxide ions, leading to a strongly alkaline solution. This is why alkali metals are named as such - 'alkali' is derived from the Arabic word for 'ashes', which were one of the first sources of alkaline substances known to humans.