why do molecules have different shapes
1 A molecule consists of 2 or more atoms joined by covalent bonds. 2  The shape of a molecule is a description of the way the atoms in the molecule occupy space. 3  A diatomic molecule, a molecule composed of only 2 atoms, must always be linear in shape as the centers of the 2 atoms will always be in a straight line. A diatomic molecule, a molecule composed of only 2 atoms, must always be linear in shape as the centers of the 2 atoms will always be in a straight line. ' 2 Electron Cloud' Repulsion Theory (Valence Shell Electron Pair Repulsion, VSEPR) is used to predict shapes and bond angles of simple molecules.