Potassium is a chemical element with the symbol K and atomic number 19. It is a soft, silvery-white metal that is highly reactive. Potassium is the seventh most abundant element in the Earth's crust and the most abundant alkali metal.

Metallic bonding is the strongest type of chemical bond. It occurs when metal atoms lose their valence electrons to form a sea of delocalized electrons. This sea of electrons holds the metal atoms together in a strong, rigid structure.

Potassium is a metal because it has one valence electron that it can easily lose. When potassium atoms lose their valence electrons, they become positively charged ions. These positive ions are attracted to the sea of delocalized electrons in the metal, which holds them together in a strong, rigid structure.