C2.5 Ionic bonds

Ionic bonds

An ion  is an atom or group of atoms with a positive or negative charge. The atoms of most elements have incomplete outer shells of electrons. This means they can lose or gain electrons during chemical reactions. When this happens, the atoms become ions. Groups of atoms may also become ions if they lose or gain electrons. 

Cations

Metal atoms lose electrons to form positively charged ions called cations. For example, sodium atoms Na become sodium ions Na+. The + sign shows that a sodium ion carriesa single positive charge.

Metal stomd lose outermost electrons when they form ions. For elements in groups 1 and 2, the number…