These are the 3 important bonds in biological molecules. Only living organisms put together and use these molecules. Ionic bonding happens when 2 ions of opposite charge attract each other and stay together. An ion is an atom that has gained or lost an electron, causing it to have a net positive or negative charge. Covalent bonding happens when atoms share a pair of electrons.
Covalent bonds are non-polar or polar.
If the atoms share electrons equally, the bond is non-polar. If the atoms sharing is NOT equal, the bond is polar - slightly positive at one end and slightly negative at the other. Because of this, one water molecule attracts and hydrogen bonds with another. Cells consist primarily of water and release a great deal of heat energy during metabolism. Hydrogen bonds in liquid water keep cells from cooking.