Now, previously, we spoke about atomic orbitals and covalent bonds. In this lecture, we'll see how atomic orbitals of atoms combine to form covalent bonds, which are really molecular orbitals. So let's begin with the following simple example. So let's say we want to combine two neutral H atoms in a way to form a diatomic H two molecule. So we want to form a covalent bond. So what must happen first?