Antimatter (Edexcel IAL Physics)

Properties of Antimatter

Spec point — 122

• The universe is made up of matter particles (protons, neutrons, electrons etc.)

• All matter particles have antimatter counterparts

  • Antimatter particles are identical to their matter counterpart but with the opposite charge

• This means if a particle is positive, its antimatter particle is negative and vice versa

• Common matter-antimatter pairs are shown in the diagram below:

This table summarises the electric charge for typical particle-antiparticle pairs

• Apart from electrons, the corresponding antiparticle pair has the same name with the prefix ‘anti-’ and a line above the corresponding matter particle symbol
• A neutral particle, such as a neutron or neutrino or photon, is its own antiparticle

Mass of Matter & Antimatter

• Although antimatter particles have the opposite charges to their matter counterparts, they still have identical mass and rest mass-energy

  • The rest mass-energy of a particle is the energy equivalent to the mass of the particle at rest

This table summarises typical particle-antiparticle pair masses and rest mass energies

Exam Hint Though you will not need to memorise individual masses or rest-mass energies, you are expected to remember the mass of a particle-antiparticle pair is identical but they have the opposite electric charge.