Video Transcript
Which of the following five
molecules contains a total of four shared electrons? (A) Methane, (B) water, (C) carbon
dioxide, (D) ammonia, or (E) hydrogen chloride.
All of the elements in these
compounds are nonmetals. Therefore, all of the bonds in all
of the molecules are covalent. Covalent bonds are chemical bonds
that are formed when two nonmetal atoms share one or more pairs of electrons. A single covalent bond contains two
shared electrons. A double covalent bond contains
four shared electrons. And a triple covalent bond contains
six shared electrons.
We can now calculate the number of
shared electrons in each of the molecules. Methane contains four single
covalent bonds. Each of the bonds contains two
shared electrons. Therefore, methane contains a total
of eight shared electrons. Water contains two single covalent
bonds. Therefore, it contains a total of
four shared electrons. Carbon dioxide contains two double
covalent bonds, which each contain four electrons. Therefore, carbon dioxide contains
eight shared electrons. Ammonia and hydrogen chloride,
however, contain six and two shared electrons, respectively.
Therefore, the molecule which
contains a total of four shared electrons is (B) water.
