Sodium is vital for life & usually found in combinaton with other more interesting elements, says Prof Allan Blackman in ep 79 of Elemental.

Would you willingly eat the product obtained from the reaction of a metal which reacts violently with water and a poisonous gas that was used as a chemical weapon in World War One?

Well, put like that you'd probably answer 'no', but chances are that you've already eaten some today, in the form of sodium chloride or salt.

Sodium the element is a highly reactive metal - the internet is full of videos of people dropping pieces of sodium in water to see the explosion that results.

This reactivity means it is never found naturally in its elemental form but exists almost always on Earth as the Na+ cation.

This cation is usually found in partnership with other more interesting anions - think, sodium bicarbonate (baking soda), sodium stearate (soap), and sodium azide (used to inflate airbags in cars).

Sodium is also a key part of the sodium-potassium pump in the human body, says Professor Allan Blackman from the Auckland University of Technology, in episode 79 of Elemental.

Go to this episode on rnz.co.nz for more details