Occurrence Of Metals In Nature
Metals occur in nature in free state or in combined state. A metal is said to occur native or free when it is found in nature in the metallic state. For example, gold may be found in nature as metal. This is because gold when left exposed to air practically does not undergo any change. It is not reacted upon by moisture, oxygen and carbon dioxide of the air. Thus, those metals which remain unaffected by moisture, oxygen and carbon dioxide of the air can occur native or free. In other words, the unreactive metals occur in nature in free state because of their low reactivity towards chemical reagents. Another example of an unreactive metal is silver.
The reactive metals, i.e., the metals which react with moisture, oxygen, carbon dioxide or other chemical reagents, are not found in nature in free state, but in combined state in the form of compounds.
Metals usually occur in combination with nonmetallic elements. The native occurrence is comparatively rare.