Question

would a molecule of methane be affected by the presence of an electric feild? explain your answer.

Answer 1

Answer is NO.

But in case of polar molecules, in the presence of an electric field, the dipole moment attracts and affects the orientation of the polar bond. This dipole in polar molecule aligns itself in the direction of the electric field.

Electronegativity of Carbon = 2.55

Electronegativity of hydrogen = 2.2

Electronegativity difference, EN = 2.55 - 2.2 = 0.35

The molecule methane has four Carbon-Hydrogen single covalent bonds. These covalent bonds are called nonpolar covalent bonds because the electrons shared by the adjacent atoms in the bonds are shared equally. The consequence of this equal sharing of electrons is that there is no charge separation (dipole moment).

Polarity of a molecule is a property of the bonds between the atoms making the molecule. Polarity refers to the separation of electric charge leading to a presence of an electric dipole in the molecule. In chemistry, polarity is attributed to the difference in electronegativity of atoms in a molecule. Electronegativity speaks to the magnitude of attraction that an atom has on the shared electrons in a bond. Nonpolar bonds occur when the difference in electronegativity between two atoms is less than 0.4, this is to say that the atoms of the molecule exert approximately the same pull on the charges, therefore no net dipole. In nonpolar molecules, the electric charges between the atoms in the molecule are equally distributed due to similar levels of attraction for the charges, as in the centres of their charges coincide.

The lack of polarity in nonpolar molecules can be a result of a nonpolar bond or due to the symmetry of its structure as is the case with Methane, both of which comprise of polar bonds which are cancelled due to its symmetrical structure.