Gallium has 39 neutrons, which is determined by subtracting its atomic number (31) from its atomic weight (70). It also has 31 electrons and 31 protons. Three of gallium's electrons are in its outermost shell and have the ability to be lost or shared.
Gallium was first isolated in 1875 by Paul-Émile Lecoq de Boisbaudran, though its existence was first suggested by Dmitri Mendeleyev. It was named after Gallia, which is the Latin name for France. Gallium is a metal that can melt at levels near room temperature. It is used in as the measuring device in high temperature thermometers. Gallium is also used in the production of semiconductors.