Buffers. So to begin, lets look at covalent bonds.
Covalent bonds involve sharing of electrons.
So each atom has equal interest in the electrons
between them. A single covalent bond involves
the sharing of one pair of electrons.
For example here, we'll look at hydrogen gas.
Hydrogens alone have a single electron in the
outermost shell which gives them a valence of one
because ideally to fill that innermost shell
they would like two electrons. So, hydrogen
will get together with another hydrogen and
they will each share the pair of electrons
so that the octet rule is satisfied and each
has a stable outer shell with two electrons.
Next, we'll look at covalent bonds sharing two
pairs of electrons or a double covalent bond.
In this case we'll use oxygen as an example. Oxygen
has six valence electrons which means that to
satisfy the octet rule, it would like to have
another two electrons in its valence shell.
It can satisfy the octet rule simply by
sharing two electrons with one other oxygen.
So oxygens now have two pairs of shared electrons
in the valence shell. Four of their own,
two pairs of shared. That equals eight. Satisfies
the octet rule. So, oxygen and oxygen or oxygen gas
is quite stable. Now, lets look at a triple covalent
bond. For example, nitrogen has five valence electrons.
In order to be satisfied, it would like to have
three additional electrons. So a triple covalent
bond involves the sharing of three pairs of electrons.
It is the strongest of the bonds that we will be
looking at in this course. So, nitrogens adding the
three more electrons sharing with another nitrogen
finally have eight electrons in the valence shell.
Three pairs of electrons form a stable molecule
of nitrogen gas. Nitrogen is really hard to break
apart. In fact there are only a hundred species of
nitrogen fixing bacteria that are able to
separate nitrogen gas. The two nitrogen molecules
and break that triple bonding arrangement to bring
all of the nitrogen that we have in the plants
that grow on earth and thus consume ourselves.
So nitrogen originates from nitrogen gas
in the atmosphere. The bond is really hard
to break because its a triple covalent bond.
The strongest of the biological bonds.