Which particle has a charge of -1?
proton
neutron
electron
nucleus

Electrons have a negative charge. 

I use this to remember

protons---> P for positive, they have a positive charge

neutrons---> neutrons sounds like NEUTRAL, they have no charge, they are neutral

electrons---> this is the last one out of three, by knowing proton are positive, and neutrons are neutral, there is only one left for electrons. they are negative.