The bond between K and Br in KBr is considered ionic. An electron is essentially transferred from K to Br, resulting in the formation of the ions K+ and Br-, which are then held together by electrostatic attraction. Covalent bonds occur when electrons are shared between atoms rather than transferred. Chemical bonds can be purely ionic, purely covalent or have characteristics of both. Bonds in which electrons are shared unequally between atoms but not transferred from one to the other are called polar covalent bonds. The Linus Scale of electronegaticities assigns a value between 0 and 4 to elements describing their attraction for electrons in a chemical bond. Nonmetals, which have a tendency to gain electrons, generally have higher electronegativities than metals which tend to lose electrons. An electronegativity difference of 0 - .6 is considered covalent, .7 - 2 is polar covalent and 2.1 and above is ionic. K has an electronegativity of 0.82 and that of Br is 2.96. The difference is 2.14, corresponding to an ionic bond.
There are two categories of atomic bonds: covalent bonds, ionic bonds.
A metal and a non-meal form an ionic bond. The non-metal attracts the electrons from the metal very easily. The ionic bond is caused by electrostatic force between the newly created negatively and positively charged ions.
Two non-metals, having similar electronegativities, form covalent bonds. The non-metals must share the electrons from their outer shells to gain stability. In an electrically balanced stable formula the total negative ionic charge is equal to the total positive ionic charge.
The ionic formula of potassium bromide is:
1 ion of `K^+` stabilizes 1 ion of `Br^-` and potassium bromide KBr is formed.