27 August 2009
Sodium, element number 11, was first isolated by British chemist Humphry Davy in 1807, who named it after soda + the -ium suffix. From the 1807 Philosophical Transactions of the Royal Society:
Potassium and Sodium are the names by which I have ventured to call the two new substances.
Soda is an older word, dating to the 16th century. The English word is taken from the medieval Latin name for an alkaline substance; it’s ultimate etymology is unknown. From William Warde’s 1558 translation of The Secretes of Alexis of Piemont Containing Remedies Against Diseases:
Take an vnce of Soda (whiche is asshes made of grasse, whereof glassemakers doo vse to make their Cristall).
The chemical symbol for sodium is Na, taken from the first two letters of natrium, a modern Latin name (coined in the 19th century) for the element, formed from the French natron, which in turn is from Arabic and ultimately Greek.
Sources:
Oxford English Dictionary, sodium, 2nd Edition, 1989.
Oxford English Dictionary, soda, 2nd Edition, 1989.
Oxford English Dictionary, natrium, 3rd Edition, June 2003.