From levitating burnt buttocks, to excitable nerves and sure-to-rise baking, potassium is highly reactive and vital to life, says Prof Allan Blackman in ep 64 of Elemental.

Potassium is a fundamental building block of life that pops up all over the place.

The name comes from the English word potash, an old term for potassium salts obtained from wood ash. The chemical symbol K comes from kalium, an Arabic term for alkaline - or al-kali- plant ashes. Germanic countries went with the common name kalium for element 19 for many years.

Potassium was discovered by the prolific element discoverer Humphrey Davy in 1807, who found it to be highly reactive with water. It also added a lovely violet colour to a flame, the same colour that is seen in the familiar potassium permanganate or Condy's crystals.

Along with sodium, potassium is a critical part of the sodium-potassium pump, which is crucial for the transmission of nerve signals.

Bananas are a good dietary source of potassium, which is an essential element.

Industrially, most potassium is used in fertilisers as well as in soaps and detergents.

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