How many electrons are shared
in a double bond between two oxygen atoms?
Oxygen is an element, and we
can find information about the element on the periodic table. The atomic number of the
element oxygen is eight. This means that oxygen atoms
contain eight protons. And since atoms are by
definition neutral, we have eight electrons as well, eight electrons to balance
out the charge of the eight protons. The question asks about
electrons shared in a double bond between two oxygen atoms. Now, oxygen is a nonmetal, so
we’d expect a certain type of bonding. And the word “shared” gives us
the start of it, co- in covalent.
Now the “valent” part in
covalent refers to the valence electrons. Valence electrons are simply
those electrons in the outer or valence shell of an atom or ion. An oxygen atom has eight
electrons and the first two fill the first electron shell. And the remaining six occupy
the second electron shell, but the second electron shell can fit a maximum of
eight electrons. We can find more electrons to
fill that available space in our second oxygen atom. Since the valence shells are
the only ones of interest here, I’m going to remove the inner shell.
If the atoms get closer
together, some of the electrons are shared between the two nuclei, helping to
produce a more stable configuration. Since this involves sharing of
valence electrons, we have a covalent bond. And since there are four
electrons involved, we’re dealing with a double covalent bond. The quick way round is just to
remember that a double covalent bond contains four electrons, a single contains
two, and a triple contains six. So how many electrons are
shared in the double bond between two oxygen atoms? Four.