Elementary particle. 

 The particles which are structure less and indivisible and are not regarded as made up of some other particles are called elementary particles. There are around 200 elementary particles discovered so far.

Fermions

- They have half integral spin: spin = ±1/2, ±3/2, ±5/2,……… and so on.

Bosons

- They have integral spin: spin = 0, ±1, ±2, ±3, … .and so on.

Leptons

- They are light particles. 

Quarks 

- Quarks are the building block of Hadrons.

- They have fractional electric charge, which violates the ‘quantization of charge’. 

- But they never exist in free. They always exist in group of either two or three quark. 

- A ‘strong force binds them within the hadrons to keep together.

Hadrons

- They are heavy particles which are made up of quarks.

- They are not an elementary particles. 

- They are classified into Mesons and Baryons.

Mesons

1.π meson 

2. k meson 

3. n meson 

Baryons 

1. Nucleons: P, n etc 

2. Hyprons : lambda,sigma xi and omega.

Quark Combination of Hadrons

- Each mesons are made from two quarks, in which one is quark and another is antiquark. 

- Each Baryons are made from three quark.