Planet Earth is able to support life because of its abundance of water. All living things depend on water to some degree. There are several properties of water that allow living cells and tissues to function properly. A water molecule has oppositely charged ends; one side is weakly positive, and one side is weakly negative. This makes it a polar substance and allows each water molecule to form hydrogen bonds with other water molecules. Water's polar nature affords it many other special properties, such as adhering to different surfaces and absorbing heat while resisting temperature change. In addition, water is less dense in its solid form and is able to dissolve many solutes that are necessary for life.

At A Glance

  • Water molecules are polar, with a partial positive charge and a partial negative charge.
  • Water molecules join together by means of hydrogen bonding, weak attractions between partial positive and negative charges.
  • Hydrophobic interactions can hold together nonpolar portions of molecules that have been pushed aside by linked groups of water molecules.
  • Water's polarity and its ability to form hydrogen bonds give it special properties, including adhesion, cohesion, and the ability to moderate temperature.
  • Water tends to dissociate into hydrogen ions and hydroxide ions, and then re-form again.
  • The pH scale measures the hydrogen ion concentration in a solution, and identifies a solution as acidic, neutral, or basic.
  • Buffers help to maintain a consistent pH by adding or removing hydrogen ions as needed.