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9.6: Unique properties of water

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  • Now, let's look at the main chemical discussed in oceanography- WATER!

    Chemical Properties of Water

    Water is made up of two hydrogen atoms (represented by H in the image above) and one oxygen atom (represented by the O in the image above). It is unique in that it is dipolar. This means that the molecule has a positive charge on one side and a negative charge on the other. The side of the water molecule where the hydrogen atoms are located ends up being positively charged, and the side of the molecule where the oxygen atom is located is negatively charged. This is because electrons are not equally distributed in the water molecule. The electrons are pulled toward the oxygen atom, resulting in its negative charge. Each hydrogen atom in water is covalently bonded to the oxygen via a shared pair of electrons. Oxygen also has two unshared pairs of electrons, thus there are four pairs of electrons surrounding the oxygen atom, two pairs involved in covalent bonds with hydrogen, and two unshared pairs on the opposite side of the oxygen atom.

    One water molecule can connect with another molecule via a hydrogen bond between a hydrogen atom of one molecule and an oxygen atom of the other. Because it has a negative side and a positive side, water molecules can easily bond to other polar or charged molecules. This can be seen by the many constituents dissolved in seawater. Their ability to dissolve is due to the polar nature of the water molecule.



    Water is a polar molecule means that there is an uneven distribution of electron density. Water has a partial negative charge near the oxygen atom due the unshared pairs of electrons,and partial positive charges near the hydrogen atoms. An electrostatic attraction between the partial positive charge near the hydrogen atoms and the partial negative charge near the oxygen results in the formation of a hydrogen bond. And the ability of ions and other molecules to dissolve in water is due to polarity.

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