This element is classified as a lanthanide and it is the most abundant of the rare-earth elements of the earth’s crust. It is the most reactive of the rare-earth metals and is used as a catalyst to refine petroleum.
This element is a transition metal used in large amounts by the electrical industry in the form of wire. This metal is the second-best in the electrical conductance. Because this element resists corrosion in air, moisture and seawater, it has been widely used in coins.
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.