Question

Descibe how electronegativity and molecular shape determine the polarity of a molecule. Then describe why chemists consider relative electronegativity values and not absolute electronegativity values when determining the polarity of a bond. Also explain how a molecule with polar bonds can be non-polar overall.​

Answer 1

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Step-by-step explanation:

Electronegativity is an idea put forward by Linus Pauling to explain the fact that in a molecule, one atom may attract the shared electrons of the bond closer to itself than the other.

Hence electronegativity is defined as the power of an atom in a molecule to attract electrons to itself.

Pauling originally described electronegativity as a relative quantity. It depends on the electronegativities of the atoms in the molecule. However, some methods have sought to measure the absolute electronegativity of a free atom.

A bond is polar when the atoms that make up the bond have a significant difference between the atoms of the molecule.

However, a molecule may possess polar bonds but may not have an overall dipole moment owing to the shape of the molecule.

For instance, CCl4 has four polar C-Cl bonds but the overall molecule is non polar because due to the fact that the molecule is tetrahedral in shape and highly symmetrical hence the individual dipoles cancel out.