This is a non-metal and the most abundant element in the Universe. It is the basic fuel for nuclear reactions in the stars. It is a gaseous substance on Earth and the lightest element in the Universe.
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 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.