Is water an element or compound?

Answer 1

Water is a compound because it is made up of two elements (hydrogen and oxygen) with polar bonds.

Historical

Of course the above is true. However in medieval times water was thought to be elemental in nature. People believed that there were 4 "elements" that composed substances: earth, air, fire and water. Everything on earth was made of some combination of these four 'elements'. There was a fifth element, the quintessence, from which we get the word quintessential, and it was thought that this element is what the stars were made of. It was also believed that this quintessence permeated everything everywhere.

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Water is a compound. It is made up of two atoms of hydrogen and one atom of oxygen, therefore its molecular structure is written 'H2O'.

Answer 2

Water is classed as a compound. Sea water which contains salts would be a mixture.
A compound - it contains the elements hydrogen & oxygen. (H2O)