Bond length varies across period
Work Step by Step
It has been shown that, for reasons related to the energy requirements for electron removal or addition, only the electrons in valence shells play a significant role in the formation of bonds between atoms. Henceforth this article will concentrate on these electrons alone. Lewis introduced the conventions of representing valence electrons by dots arranged around the chemical symbol of the element, as in H· and Na·, and of discussing bond formation as the transfer of dots from one symbol to another. This seemingly simplistic device turns out to be very useful for establishing the characteristics of chemical bonds and will be examined in this section.