Structural Biochemistry/Unique Properties/Structure of Water

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A water molecule with its important properties highlighted

Structure of Water[edit]

1. A water molecule is composed of two hydrogen atoms and one oxygen atom[1]

2. Two lone-pair electrons from the oxygen atom make two lobes of negative density in the overall molecule
3. Large dipole moment—gives 33% ionic character to O-H bonds
4. Large polarizability
5. The H-O-H angle is 104.3 degrees[2]

Quick Brief about the importance of the structure of water[edit]

The structure of water contributes tremendously to its unique properties. Water has two Hydrogen atoms attached to an Oxygen atom give it some partial charges due to Oxygen's great electro-negativity. These partial charges are what make it possible for water to form hydrogen bonds.[3]

It is also due to its bent shape, due to the two lone pairs of electrons, which allow it to have this dipole moment. If it was linear, then it would not contain a dipole because both individual dipole's would be pulling against each other, thus canceling. Thanks to the electron pairs and their repulsions, water is in a bent shape, and the polarity is allowed to exist.

More about water molecule structure[edit]

Water molecule is composed of one Oxygen and two Hydrogen atoms. Together with its two lone electron pairs, the Oxygen atom bonding to two Hydrogen atoms nearly forms a 3D tetrahedral structure. X-ray and neutron diffraction has been used to confirm liquid water tetrahedral structure.[4] The nearly tetrahedral structure of the orbitals around the oxygen atom allows one liquid water to form three Hydrogen bonds with four other water molecules. The Hydrogen bonds that are formed between a Hydrogen on one water molecule and the oxygen of another water molecule are not as strong as the covalent bonds between a hydrogen and oxygen atom on the same water molecule. Hydrogen bonds are longer and weaker than covalent O-H bonds[5]


  1. Viadiu, Hector. "Water." UCSD, 5 October 2011.
  2. Viadiu, Hector. "Water." UCSD, 3 October 2011.
  3. Viadiu, Hector. "Water." UCSD, 3 October 2011.
  5. Viadiu, Hector. "Water." UCSD, 5 October 2011.