Spherical molecules: Covalent bonds
The nuclei of the gravitational systems (atoms, stars) rotate on themselves (spin) and they make to rotate and to be deformed (in spiral) to the gravitational and magnetic fields that surround them.
This makes that to be able the approaching and union of two or more atoms and to create common orbits (covalent bonds) they have to join in the polar N-S direction, because otherwise their magnetic and gravitational fields would collide producing the rejection among them.
Therefore, to come closer some atoms to other and to create the atomic connections or to build crystals, atoms must approach in the polar direction N-S or S-N
