The elements that make up Group 13, the boron family, are boron, aluminum, gallium, indium and thallium. All elements have three valence electrons, the electrons in the most outer shell. All elements in the boron family are metals except for boron, which is a metalloid.
Boron is the smallest element of the group, with an atomic number of 5 and atomic weight of 10.8. Its symbol is B. Pure boron does not exist in nature. Aluminum is an active gray metal with an atomic number of 13 and atomic symbol of Al. It is the most abundant metal found in the Earth's crust. Gallium has an atomic number of 31 and atomic symbol of Ga. It has the second lowest melting point and can remain in a liquid phase for a long time. Indium has an atomic number of 49 and atomic symbol of In. It is a silver-white metal. Thallium is a heavy metal with the atomic symbol Ti and atomic number 81.