Atoms, as mentioned, are the smallest possible parts of matter. Inert gases or noble gases are the only elements in their natural state, that do not react in order to form molecules. Hence, atoms of such gases exist in an independent state. Atoms of these noble gases are deployed for research, often termed as nuclear physics.
According to research, the central part of an atom is highly charged, and is dense with matter. Protons and neutrons are included in the nucleus. Electrons, on the other hand, revolve around it. The nucleus of a hydrogen atom, which is supposed to be amongst the smallest, is 1.6 fm (1.6 × 10−15 m), while that of a uranium atom is 15 fm (15 × 10−15 m).
A nucleus is primarily made up of two baryons, protons and neutrons. Protons and neutrons are bound within the nucleus, with the help of a charge known as nuclear force. Nuclear force is also sometimes referred to as residual strong force.
Scientists studying nuclear physics have inferred that protons and neutrons are further made up of matter, known as 'quarks' or simply sub-atomic matter. Strongly bound quarks become baryons, and are classified according to their charge; a positively charged baryon becomes a proton, while a neutral charged baryon becomes a neutron.
Atoms of some elements have a third baryon, called the hyperon. This type of baryon does not exist on earth in its natural state. It can however, be created, and is used in experiments of nuclear physics in a highly controlled environment.
During the process of nuclear fission, when the nucleus splits, this residual force is converted into heat energy.
In spite of warnings given by early scientists who initiated research of atomic nuclei, scientists today still perform what is known as nuclear fission. Nuclear fission is a nuclear reaction that splits the nucleus into smaller parts, thereby, completely destroying its original and actual structure.
If used wisely, an atomic nucleus can be put to a very good use, like generation of electricity. However, if put to wrong use, like in nuclear weapons, it is even capable of wiping out the entire human race.