what is smaller than an atom

Is there anything; smaller than an atom that exists in the universe?
The simple answer is yes, the composite and elementary particles are smaller than an atom. Sometimes, composite and elementary particles are called subatomic particles. Protons and Neutrons are the composite particles, while quarks and leptons are elementary particles that have no internal substructure, i.e., elementary particles are not composed of other particles.

Every atom consists of three particles, which are:

  • Electrons
  • Protons
  • Electrons

What is Proton?

Proton is a positive charge particle and exists inside the nucleus of an atom. The charge on a proton is +1e elementary charge. The mass of a proton is slightly less than that from a neutron.
Hydrogen is the simplest atom and has only one proton while other atoms have many protons in their nucleus.
The number of protons in the nucleus of an atom helps in determining the atomic number of an atom. Since each element in nature has a unique number of protons and hence each element has a unique atomic number.
According to the standard model, protons are composites particles and composed of three quarks, two up quarks, +2/3e, and one down quark -1/3e.

 

What is the size of protons?

Two different techniques show that the radius of the proton is approximately 0.833 fm, with an uncertainty of ±0.010 fm.

What is a neutron?

Neutron is a subatomic particle and is a neutral particle in the nucleus of an atom. Neutron has a mass slightly greater than a proton. The number of neutrons can vary, for example, deuterium and tritium are the isotopes of H-atom. These isotopes have the same number of protons while a different number of neutrons. The nucleus of deuterium has two and the tritium has three neutrons. The mean square radius of the neutron in about 0.8×10−15 m, or 0.8 fm.

What are the nucleons?

The neutron and protons in the nucleus of an atom are called nucleons. The nucleons are holds to gather by the strong nuclear force.

What are quarks?

Quarks are elementary particles and combine to form composite particles (neutrons and protons).

Quarks have six types, and which:
up (u), down (d), strange (s), charm (c), bottom (b), and top (t)
Two up and one down quarks combine and form a proton, and two down and one up quarks make a neutron.