The one eV of energy is given up to other particles as the electron crashes into the positive end. This proton collision is similar to the proton beam collision with a target at Fermilab, but at Fermilab the proton energy is much greater. When the particle slows down or collides with another particle the extra mass may be converted back to energy of motion or it may form new particle mass.
Every particle is either neutral or has an electrical charge that never changes.
The charge of an electron is negative. There are other quantifiable properties of particles including spin and magnetism. The quark, considered to be one of the most fundamental particles, has additional properties given fanciful names such as color and flavor.