What are the properties of lithium, sodium, and potassium?

Lithium, sodium, and potassium are all alkali metals, characterised by their reactivity, softness, and low density.

Lithium, sodium, and potassium are part of the alkali metals group in the periodic table. This group is known for its elements' reactivity with water and air, which increases as you move down the group. This means that potassium is more reactive than sodium, which is more reactive than lithium. They all have a single electron in their outer shell, which makes them highly reactive and eager to donate this electron in chemical reactions.

Lithium is the lightest of the alkali metals and has the highest melting point. It reacts with water, but not as vigorously as sodium or potassium. When it does react, it forms lithium hydroxide and hydrogen gas. Lithium is often used in batteries due to its high electrochemical potential.

Sodium is a soft, silvery-white, highly reactive metal. It is slightly heavier than lithium but lighter than potassium. Sodium reacts explosively with water to form sodium hydroxide and hydrogen gas. This reaction is more vigorous than that of lithium. Sodium is commonly used in table salt (sodium chloride) and baking soda (sodium bicarbonate).

Potassium is a soft, silvery-white metal, heavier than both lithium and sodium. It reacts violently with water, even more so than sodium, to form potassium hydroxide and hydrogen gas. This reaction is often accompanied by a lilac flame. Potassium is essential for plant growth and is a key component of fertilisers.

All three metals are soft and can be cut with a knife. They have low densities and float on water. They also have low melting and boiling points, which decrease down the group. These properties make lithium, sodium, and potassium unique and interesting to study in chemistry.