Summary

Charge is quantized, integer multiple of e=1.6x10^{-19}.
q=\pm ne
Coulomb's law: F=k\frac{p_1p_2}{n^2}; directly proportional to charge, inversely proportional to distance.
Same signs repel, opposite signs attract.
Electric force is stronger than gravity for tiny particles, gravity controls large scale because big objects are usually neutral.
Electric permittivity measures how much a material polarizes in a field. Conductors let charge move freely, insulators don't.
Only need to calculate force for 4 or less interacting charges unless situation is highly symmetrical.