ion

When a neurotransmitter binds to a receptor, it unlocks an internal channel, allowing small ions to flow into the cell.

You can have strings of atoms that are missing or have extra electrons, so they're ions, they're electrically charged.

Liquid petroleum packs a lot of energy into not much space, to the point where the average lithium-ion battery carries anywhere from 50 to 100 times less energy than an equivalent amount of gasoline.