Although there are a little more than 100
different elements in the world, only a small number comprise a majority of the
different systems on Earth. The elements that make up rocks and minerals of
solid Earth include silicon, oxygen, iron, magnesium, and other trace amounts
of various elements. Living organisms are composed primarily of carbon, oxygen,
and hydrogen. Other elements in living matter include calcium, nitrogen,
phosphorus, potassium, and trace amounts of other elements.
