Lithium is the lightest metal, and it is used in batteries and for the treatment of bipolar disorder, says Prof Allan Blackman from AUT in ep 45 of Elemental.

Lithium is the lightest metal on the periodic table and the lightest solid element.

Lithium (symbol Li, atomic number 3) is also the most reducing element - it has a single outer electron that it is desperate to give away so it can form lithium ions. This characteristic makes it invaluable in lithium ion batteries such as those used in electric vehicles.

It is useful in light aluminium-lithium alloys that are important components of bikes, planes and high-speed trains.

Lithium carbonate is widely used in the treatment of bipolar disorder, although we remain unsure exactly how it works in the human brain, says Allan Blackman from AUT in episode 45 of Elemental.

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