Discovery of Sodium

In 1806 Sir Humphry Davy discovered that chemical bonding was electrical in nature and that he could use electricity to split substances into their basic building blocks – the chemical elements.

In 1807, at the Royal Institution, London, a few days after isolating potassium for the first time, he isolated sodium for the first time by electrolysis of dried sodium hydroxide, which had been very slightly moistened.

The electrolysis was powered by the combined output of three large batteries he had built.

Davy noted that the metal which formed at the wire electrode he placed in the sodium hydroxide was a liquid, but became solid on cooling and “appeared to have the lustre of silver.”

“It is exceedingly malleable and is much softer than any of the common metallic substances… this property does not diminish when it is cooled to 32 ^oF (0 ^oC).”

Davy also noted that, when added to water, sodium decomposed the water, releasing hydrogen.

He asked whether the new substance should be classed as a metal and noted that most other scientists thought it should, despite the fact that its density was much lower than the other metals then known:

“…for amongst the metals themselves there are remarkable differences in this respect, platina [we now call it platinum] being nearly four times as heavy astellurium.”

He named the new metal sodium, because he had used caustic soda or, more simply, soda, as his source of the element. 

In Germany caustic soda was known as natronlauge and L. W. Gilbert suggested the new element should be called natronium.

J. J. Berzelius preferred the shorter natrium, from which we get the chemical symbol for sodium, Na. 

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