Which formula represents a nonpolar molecule?

Regents Chemistry Exam January 2025 Question 9.

9 Which formula represents a nonpolar molecule?

(1) CH4

(3) H2O

(2) HCl

(4) NH3

Solution:

A polar molecule is a molecule that has an assymetrical distribution of charge resulting in an overall dipole moment. A nonpolar molecule has a symmetrical distribution of charge. In order to determine whether the molecule is polar or not, we must first draw out the correct Lewis Dot structure.

Mayya's Trick

A Molecule is NONPOLAR if

It consists of two of the same atoms. Example: H2, O2, N2

OR

The central atom is attached to the same atoms AND has no lone pairs of electrons (there are exceptions but not relevant to regents).

For example. CO2(carbon is attached to all the same atoms, oxygens, and the shape of the molecule is linear).

CH4 is a nonpolar molecule because the central atom, carbon, is attached to all the same atoms (hydrogens) and has no lone pairs. Choice 1 is the correct answer.

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