Video Transcript
What type of bond is the CH
bond? (A) Nonpolar covalent bond, (B)
polar covalent bond, (C) ionic bond, or (D) hydrogen bond.
The first three answer choices are
all examples of intramolecular forces. These are forces that bind atoms or
ions to make up molecules or compounds. Hydrogen bonds are a type of
intermolecular force, forces which act between neighboring particles. More specifically, a hydrogen bond
is the force of attraction between a hydrogen atom in one molecule and the lone pair
electrons on a highly electronegative atom in a different molecule.
In this question, we want to know
what type of bond exists between a carbon atom and a hydrogen atom. As we want to know what type of
bond exists between two atoms and not two different molecules, we can eliminate
answer choice (D). We can think of the remaining
answer choices as part of a bonding spectrum. On one side of the spectrum, we
would find bonds in which the bonding pairs of electrons between two atoms are
equally shared. This is called a nonpolar covalent
bond. On the other side of the spectrum,
we find ionic bonds. Here, the atoms don’t share
electrons but rather transfer electrons to form positively charged cations and
negatively charged anions that are electrostatically attracting.
In the middle of the spectrum, we
find polar covalent bonds in which the bonding pair of electrons is unequally shared
between the two atoms. We can get a sense of what type of
bond would form between two elements by looking at the electronegativity of each
element. Electronegativity is the tendency
of an atom to attract the shared electrons of a bond. Nonpolar covalent bonds form when
the electronegativity of the two atoms is similar as each atom attracts the
electrons to a similar degree. Ionic bonds form when the
electronegativity of the two atoms is so drastically different that the electrons
aren’t shared at all.
In general, if the difference in
electronegativity between atoms is less than 0.4, the bond will be nonpolar
covalent. If the difference is greater than
1.8, the bond will be ionic. And anything in between would be
polar covalent. Carbon has an electronegativity
value of 2.55, while hydrogen has an electronegativity value of 2.2. The difference between these two
values is 0.35, which is less than 0.4, indicating that the type of bond is nonpolar
covalent. Therefore, answer choice (A),
nonpolar covalent bond, is the correct answer.
