This creates electrically charged atoms, or ions. These attract each other and create an ionic bond. Cluster of atoms held together by covalent bonds. Different atoms form different number of bonds based on the number of electrons in their outer shell. Molecules can rotate around single bonds, but not around double bonds.
Some atoms attract shared electrons to different degrees in covalent bonds.
In these cases, the positive charge is concentrated towards one end and the negative charge towards the other. This is called a polar covalent bond. Another non-covalent bond is the hydrogen bond.