The physical and chemical properties of elements and compounds are a function of their structures. As we have seen in previous chapters, ions form when electrons are transferred from one atom to another. The crystalline structure and specific properties of ionic compounds are related to the nature of the ionic bond. Molecular compounds form in a completely different way. As you will learn in this chapter, atoms are also capable of forming chemical bonds by sharing electrons. There are specific guidelines that can be used to determine the ways in which this sharing occurs and the shapes of the molecules that result. The picture above is an electron density map of a water molecule, which has a bent shape. The red color is indicative of high electron density, while the blue color is indicative of low electron density.
Ben Mills (Wikimedia: Benjah-bmm27). commons.wikimedia.org/wiki/File:Water-elpot-transparent-3D-balls.png. Public Domain.