Compounds and Elements in the Earth

Compounds and Elements in the Earth

Dry air consists of gases, some of which are elements (for example, oxygen, nitrogen and argon) and some of which are compounds (for example, carbon dioxide).
The relative proportions of the main gases in the atmosphere are about 78% nitrogen, 21% oxygen, 1% argon and 0.04% carbon dioxide.

The Earth’s hydrosphere (oceans, seas, lakes and rivers) consists mainly of water with some dissolved compounds, called salts.

The Earth’s lithosphere (the rigid outer layer of the Earth made up of the crust and the part of the mantle just below it) is made up of a mixture of minerals. Silicon, oxygen and aluminium are very abundant elements in the Earth’s crust. Much of the silicon and oxygen is present in the Earth’s crust as the compound silicon dioxide