Final answer:
The combination of two atomic orbitals results in the formation of two molecular orbitals, known as bonding and antibonding orbitals. The number of molecular orbitals formed is equal to the number of atomic orbitals that combine.
Step-by-step explanation:
The combination of two atomic orbitals results in the formation of two molecular orbitals. These are termed bonding orbitals and antibonding orbitals. When atomic orbitals combine, the bonding molecular orbital is generally stabilized and lower in energy than the individual atomic orbitals, while the antibonding molecular orbital is destabilized and higher in energy. It is also important to note that the interaction between atomic orbitals is greatest when they have the same energy, contributing to the formation of these molecular orbitals.
For example, if two He 1s atomic orbitals combine, they would produce a lower energy 1s bonding orbital and a higher energy 1s* antibonding orbital. If we consider a scenario where five atomic orbitals from atom A and five atomic orbitals from atom B combine, a total of ten molecular orbitals would result, mirroring the input number of atomic orbitals. As such, the general rule of thumb is that the number of molecular orbitals formed is equal to the number of combining atomic orbitals.