Question

Why are most materials compounds rather than elements?

Answer 1

Because elements are reactive? And formation of compounds is thermodynamically downhill.

Explanation:

As a matter of fact, while the air we breathe is a mixture, it is a mixture of elemental gases, mostly dinitrogen and dioxygen. Looking at the composition of the Earth's crust, there is still a great deal of elemental carbon as coal (and much more rarely as diamond). Other elements in the Earth's crust include certain precious metals; gold is probably the most common.