The elements of atomic number 57 through 71 are known as the Lanthanide elements. This name for the group is no longer appropriate because most of them are available in far greater quantities than originally thought. In fact the absolute abundances in the lithosphere are relatively high. The rare-earth elements are all metals. They are all sufficiently reactive that none exists in nature as the elemental metal.
Reduction can only occur in combination with oxidation .
The balanced half-reaction that is written to show the gain of electrons that occurs during reduction . Refluxing The process of boiling a liquid in a vessel connected to a condenser, so that the liquid runs back into the vessel. By using a reflux condenser, the liquid can be maintained at its boiling point for long periods of time, without evaporation. The technique is a standard method of carrying out reactions in organic chemistry. All the 'A' group elements in the periodic table.