Chapters 7 and 8 dealt with isolated atoms and their electronic properties.
Many chemists are interested in molecules and compounds.
All the tremendous variety of materials found in our physical world may be interpreted and understood as a combination of about 100 elements. Chemical Abstracts registers compounds and gives each one a number - over 7 million have been registered and there are 17 million names. A chemical bond is the glue which holds atoms together to make more than one atom molecules and ionic substances. Covalent bond - a chemical bond formed by the sharing of a pair of electrons between atoms. When atoms interact to form a chemical bond, only their outermost regions are in contact.