(a) What is meant by the term orbital overlap? (b) Describe what a chemical bond is in terms of electron density between two atoms.

Orbital overlap refers to the interaction of atomic orbitals from two different atoms as they come close to each other. It occurs when the regions of electron clouds from adjacent atoms partially occupy the same space, leading to a sharing of electrons between the atoms. This interaction results in a stabilization of energy for the system and contributes to the formation of chemical bonds.

In molecular orbital theory, the degree of orbital overlap between two orbitals directly affects the strength of the chemical bond formed between the atoms. A greater overlap results in a stronger bond, as the electrons become more delocalized and the energy of the system is lowered. On the other hand, a weak or no overlap between orbitals can result in weak or even no bonding.

A chemical bond is an attractive force that holds together two or more atoms in a molecule or compound. It involves the sharing or transfer of electrons between the atoms, resulting in a stable arrangement of electron densities around the nuclei that minimize the overall energy of the system.

In terms of electron density, a chemical bond can be described as a region of high electron density between two atomic nuclei, where the electrons are more likely to be found. When two atoms approach each other, their electron clouds interact, leading to the overlap of their atomic orbitals and providing a pathway for electron sharing or transfer. As the electron density between the atoms increases, their positively charged nuclei are attracted to the negative electron density region, thus forming a stable chemical bond. Different types of chemical bonds (e.g., covalent, ionic, and metallic) can be explained by considering the variation in electron density between different atoms and the way that electrons are distributed in the resulting bond.