Question

Two atoms of hydrogen combine to form a molecule

of hydrogen gas, the energy of the H2 molecule is :
(1) Greater than that of seperate atoms
(2) Equal to that of seperate atoms
(3) Lower than that of seperate atoms
(4) Some times lower and some times higher

Answer 1

lower than the separate atoms. Because an electron in this molecular orbital is strongly attracted to both nuclei, the electron is more stable (at lower energy) than it is in the 1s orbital of the hydrogen atom. Because it concentrates electron density between the nuclei, the bonding molecular orbital holds the atoms together in a covalent bond.