Each particle has a corresponding antiparticle with the same mass but opposite values for all other properties (e.g. strangeness, charge). Examples of particle-antiparticle pairs include: electron-positron, proton-antiproton, neutronantineutron, neutrino-antineutrino. 
Hadrons:
- Composed of quarks so not fundamental
- Subject to strong nuclear force
- Baryons and mesons 4. g. protons and neutrons
Leptons:
- Fundamental
- Subject to weak nuclear force
- Electrons and neutrinos
The quark model of hadrons proposes that hadrons consist of a combination of 6 quarks: up, down, top, bottom, strange and charm (and their respective antiquarks).
Quark Charge / e Strangeness
Up 
0
Down −(1/3) 0
Strange −(1/3)
The antiparticles of these quarks have the opposite charge and strangeness, but the same mass. Protons are uud; neutrons are udd.
There are four fundamental forces in nature:
| Fundamental force | Effect | Relative strength | Range (m) |
| Strong nuclear | On nucleons | 1 | ~10-15 |
| Electromagnetic | On charged particles | 10-3 | Infinite |
| Weak nuclear | Responsible for β-decay | 10-6 | ~10-18 |
| Gravitational | On all particles with mass | 10-40 | Infinite |
Beta decay is the emission of electrons or positrons. The force responsible for it is the weak nuclear force. It involves changes to neutrons or protons.
- 10n → 11p + −01e + ̅
- This can be explained in terms of quark transformations: d → u + −01e + ̅ β+ decay:
- 10p → 11n + +01e +
- This can be explained in terms of quark transformations: u → d + +01e +
In both cases, charge is conserved.