Why is water considered a polar molecule?
A) The oxygen atom is found between the two hydrogen atoms.
B) Both hydrogen atoms are at one end of the molecule, and the oxygen atom is at the other end.
C) The oxygen atom attracts the hydrogen atoms.
D) The oxygen end of the molecule has a slight negative charge, and the hydrogen end has a slight positive charge.
The Correct Answer and Explanation is :
The correct answer is D) The oxygen end of the molecule has a slight negative charge, and the hydrogen end has a slight positive charge.
Explanation:
Water (H₂O) is considered a polar molecule due to the way its atoms are arranged and the distribution of electrical charges. A molecule is polar if it has a positive charge on one side and a negative charge on the other, creating a dipole. In the case of water, this polarity arises from the unequal sharing of electrons between the oxygen and hydrogen atoms.
Oxygen is more electronegative than hydrogen, meaning it attracts electrons more strongly. In a water molecule, the two hydrogen atoms are covalently bonded to the oxygen atom. However, because oxygen is more electronegative, the shared electrons spend more time closer to the oxygen atom than to the hydrogen atoms. This results in a partial negative charge (δ-) on the oxygen atom and partial positive charges (δ+) on the hydrogen atoms.
The shape of the water molecule also plays a role in its polarity. The molecule adopts a bent or V-shape, with the oxygen atom at the vertex and the hydrogen atoms at the ends. This asymmetrical arrangement ensures that the positive charges from the hydrogen atoms do not cancel out the negative charge from the oxygen atom. As a result, the water molecule has a net dipole, where one end is slightly negative (the oxygen side) and the other end is slightly positive (the hydrogen side).
This polarity gives water some of its unique properties, such as high surface tension, the ability to dissolve a wide range of substances (solvent properties), and the formation of hydrogen bonds between molecules. These properties are crucial for life processes, making water a vital substance for biological systems.