Video Transcript
Fill in the blanks. N2 is a blank molecule and has a blank bond. (A) Nonpolar, nonpolar. (B) Polar, polar. (C) Nonpolar, polar. Or (D) polar, nonpolar.
In this question, we want to know about the polarity of a nitrogen molecule and the
bond within it. To determine the polarity of a bond, we can reference the electronegativity of the
atoms. The electronegativity of an atom is its tendency to attract bonding pairs of
electrons from a chemical bond. The absolute difference of the electronegativity values can tell us about the
polarity of the bond. 𝐸 one and 𝐸 two are the electronegativity values of the two bonded elements. The electronegativity values we will use will be the unitless values from the Pauling
scale.
By calculating the difference of electronegativities, we can identify the bond type
as either pure covalent, nonpolar covalent, polar covalent, or ionic. An electronegativity difference of zero denotes a pure covalent bond. For example, diatomic hydrogen has a pure covalent bond since the two hydrogens have
the same electronegativity, and thus the difference is zero.
Nonpolar covalent bonds have an electronegativity difference of less than 0.4. For example, the carbon-to-hydrogen bonds in methane have an absolute
electronegativity difference of 0.35. This means methane contains nonpolar covalent bonds.
Polar covalent bonds have a range of electronegativity differences between 0.4 and
approximately 1.7. For example, the bond in hydrogen chloride has an electronegativity difference of
0.96. This means it contains a polar covalent bond.
A bond is considered ionic when it has an electronegativity difference greater than
approximately 1.7. For example, bonds in sodium fluoride have electronegativity differences of 3.05. So it contains ionic bonds.
There are only two nitrogen atoms in the nitrogen molecule, with a triple bond
between them. Because the atoms in the bond are the same element, the electronegativity difference
will be zero. We can calculate this using the electronegativity of nitrogen, which is 3.04. The absolute electronegativity difference is the absolute value of 3.04 minus 3.04,
which equals zero.
With bonding only occurring between two atoms in the molecule, the molecule overall
is also nonpolar due to the even distribution of charge. So the correct answer is (A) nonpolar, nonpolar. We can now fill in the blanks. N2 is a nonpolar molecule and has a nonpolar bond.
