What are polar and non-polar molecules?

Polar molecules:

Polar molecules must grasp polar bonds due to a distinction in electronegativity between the bonded atoms. A polar molecule having two or more polar bonds formed an asymmetric geometry so that the bond dipoles do not cancel each other effects.

Polar molecules magnetize each other in the course of dipole-dipole intermolecular forces and hydrogen bonds. Polarity induces a number of physical properties for example surface tension, solubility, melting, and boiling points of Polar molecules.

Examples of polar molecules are Ammonia (NH3), Sulfur Dioxide (SO2) and Hydrogen Sulfide (H2S) etc.

Nonpolar molecules:

A molecule is known as nonpolar either due to an equal sharing of electrons among the two atoms of a diatomic molecule or due to the symmetrical arrangement of polar bonds in most complex molecules. Examples of non-polar molecules are; Nitrogen (N2), Oxygen (O2), Carbon Dioxide (CO2), Methane (CH4), Ethylene (C2H4) etc.

Is NO2 Polar or Non-Polar?

Here are some points which show that NO2 is a polar molecule.

Geometry of the Molecule:

We can say NO2 is a polar molecule. When we draw the structure of NO2 geometry of the molecule is bent due to the non-bonding pair of electrons. The bent geometry induces the polarity.

If the NO2 molecule had linear geometry, the polar bonds would cancel each other effect and the molecule would be non-polar but here the situation is opposite, a lone pair of electrons is also present on nitrogen. The pair of electrons repel the bonds due to high repulsive forces of lone pairs the molecular geometry distort and formed bend geometry. The polar bonds do not negate each other, assemblage the polar molecule.

Electronegativity difference:

Electronegativity difference also creates polarity. The polarity of the bond can be calculated by noting the electronegativity difference of bonded atoms: If the electronegativity difference of two atoms is from 0.4 to 1.7 then the polar bond formed. If the electronegativity difference of two atoms is less than 0.4, then it formed a non-polar bond.

E.N of Nitrogen = 3.04

E.N of Oxygen = 3.44

Electronegativity difference =3.44-3.04

                                                  =0.4

0.4 is Electronegativity difference it shows that NO2 is polar molecule.

Oxygen is more electronegative than nitrogen and pulls the electrons from the surroundings of the bond. They are unequally dispersed. Therefore, it formed an N-O polar bond with the oxygen negative and the positive charge on nitrogen.

Electron Density:

Bond polarity takes place when the electron density build-up towards one end of a bond, due to which a slight negative charge takes place at that end and the other end a slight positive charge automatically. This happened because of a difference in electronegativity of the two atoms that share the electrons.

Covalent Bonds:

Nitrogen formed 3 covalent bonds, with one remaining lone pair giving its geometry more tetrahedral than planar, so that even if you had 3 similar elements bonded to it, there would be asymmetry consequently giving it minor polarity.

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