Ionic bonding involves a metal and a non-metal. This is because ionic bonding involves the transfer of valence electrons. The resulting bond creates two oppositely charged ions.
Ionic bonding occurs between metals and non-metals because metals have few electrons in the outermost ring. This makes metals more ready to lose electrons, as that will lead to the ion obtaining a stable configuration. Some non-metals have close to eight electrons and require more electrons to obtain noble gas configuration.
More than one electron can be shared between elements. As one element gains and another loses, this leads to one element becoming positively charged and the other negatively charged. Whether the element becomes positive or negative depends on if they have lost or gained electrons. A loss will lead to a positive charge, while an additional electron leads to a negative charge. The net charge in the compound must be zero. As it is always the metal donating electrons, the metal element is positive and the non-metal element is negative.
An example of an ionic bond is the compound sodium chloride, which is commonly known as table salt. Sodium contains one electron in its outermost ring, while chlorine contains seven. The sodium transfers its electron to the chlorine and becomes positively charged, while the chlorine becomes negatively charged. The net charge of the compound is zero, as the two elements have bonded.