The separating of humans into individual elements, or atoms, such that they're disconnected from each other.

Basically, breaking the social bonds that once held human society together. A community is very strong, a group of individuals with no connection to each other is weak. What union-busting does to the workplace, atomization does to society at large. Individualism is tangential but not quite the same. Individualism is a sort of ideology that things should be this way. They should be self-reliant and depend on themselves etc etc. Atomization is the state being unable to form meaningful social relationships due to isolation.