This is a non-metal and it is a structural element of all biomolecules and living beings. Three naturally occurring allotropes of this element are known to exist: amorphous, graphite and diamond.
This element is the lightest alkali metal and it is very reactive. This metal is used for the production of dry cells and storage batteries (for cell phones, car batteries, etc.). The carbonate of this metal is used for the treatment of some mental decease.
This element is classified as an actinide and it is solid at room temperature. It is a synthetic transuranic element and can be produced in kilogram quantities. It is used in smoke detectors and as a portable source of gamma rays.