gallium (Ga) /gal″ē·əm/ [L, Gallia, Gaul] , a metallic element. Its atomic number is 31, and its atomic mass is 69.72. The melting point of gallium is 29.8° C (88.6° F); it will melt if held in the hand. Because of its high boiling point (1983° C; 3602° F), it is used in high-temperature thermometers. Radioisotopes of gallium are used in total body scanning procedures. Many of its compounds are poisonous.
