During the Quark Epoch the strong force and soon
after the electromagnetic force breaks off from the super force;
which just leaves the weak force as the last force. It was also
during this time that the temperature of the universe dropped
below 10^13k which signifies that protons and neutrons could no
longer be produced in pairs. Ends around 10^-4 seconds after the
big bang
During this time the universe was still hot enough
for leptons to be produced in pairs, compared to protons and
neutrons, leptons have less mass and are thus still able to be
produced in pairs while in a cooler universe. Lepton pair
production would cease when the universe would drop below one
billion kelvin which would be around 10^2 seconds after the big
bang.
Matter begins to form once the temperature of the
universe has cooled enough for protons and neutrons to combine
and create nuclei. This is referred to as Nucleosynthesis,
however, at this point in time the nuclei were not yet neutral
because the universe was full of photons that would keep
exciting electrons, these electrons were all over space (like a
sea of electrons) and would also interact with photons which
would have given the universe and opaque look.