In general there is one proton and one electron.
But it can be also:
proton + neutron + electron
proton + 2 neutrons + electron
proton + 3 neutrons + electron
proton + 4 neutrons + electron
proton + 5 neutrons + electron
proton + 6 neutrons + electron
proton + 7 neutrons + electron
I think it ends here for now, perhaps Mitch will have something to add