Gaining electrons changes an atom into a negative ion. Group 2 metals commonly lose two electrons to form ions with two positive charges. Other metals, like the transition metals, also always form positive ions, but the number of electrons they may lose varies. Nonmetals form ions by gaining electrons.
Metal elements form positively charged ions called cations because they are located on the left side of the periodic table. Groups 1 and 2 are called the alkali metals and alkaline Earth metals, respectively. These elements all have valence electrons in an s orbital.
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