The document is an internal assessment submission by Sneha Manjul, a student in M.Sc. Semester III at Isabella Thoburn College in Lucknow, on the topic of molecular orbital theory. It introduces molecular orbital theory, which describes atomic bonding in terms of molecular orbitals formed from the combination of atomic orbitals. It outlines the principles of molecular orbital theory, including that molecular bonds have lower potential energy than separate atoms and that bonding and antibonding molecular orbitals form. It also discusses sigma and pi bonds, and how molecular bond order relates to bond strength and molecular stability.