posted by Sheryl .
Lithium atoms, like hydrogen atoms, have only a single electron in their outer shells, yet lithium atoms do not join together to form Li2 molecules the way hydrogen atoms form H2 molecules. Instead, lithium is a metal with each atom part of a crystal structure. Can you think of the reason for this difference?
H bonds together because each atom shares its electron and it takes only two electrons to fill the shell in H atoms. Li atoms must have 7 electrons if they tried to share their electrons. It is easier for them to lose the outside electron leaving the inner shell filled.