Explain chemical bonds in basic chemistry?

Chemical Bonds :  Chemical bonds are forces that join atoms together in a functional unit. There are three types of bonds that can occur between atoms: ionic bonds, covalent bonds, and hydrogen bonds. Ionic bonds hold atoms together in crystals. Ionic bonds are formed when a positively charged atom, usually a metal, completes its outer shell by borrowing elecron(s) from a negatively charged nonmetal. Covalent bonds form when atoms share electrons to form the molecules that compose compounds, substances with different physical and chemical properties than the component atoms. For instance, hydrogen gas and oxygen gas join to form water, a liquid. Hydrogen bonds tend to make water and certain other compounds more cohesive and adhesive. Van der Waals forces and hydrophobic interactions are weak nonpolar associations important in living cells.