Hydrophobic things are things that repel water. Examples of these are alkanes, oils, fats, and most greasy substances. Hydrophobic substances are nonpolar substances that mostly have a long chain of carbon molecules that don’t interact with water molecules. When a hydrophobic substance is dropped in water the hydrogen bonds in the water molecules are broken to make space for the new substance, but the water molecules do not react to the hydrophobic substance. New hydrogen bonds are made by the water molecules around the substance creating a cage of water making the substance more ordered. There are factors that will affect the strength of hydrophobic interactions. The more carbons there are on the hydrophobic substance the greater the strength of the hydrophobic interactions i=will be. Also the hotter the temperature is the stronger the interaction becomes. Hydrophobic interactions are very important in biology. They serve many purposes such as making up the phospholipid bilayer in all cells of the body.