Atomic nucleus

(A) Introduction
1. Atomic nucleus exists at the center of the atom. Nucleus of an atom consists of entire positive charge of the atom and almost all of its mass.
2. Nuclei is made up of protons and neutrons out of which protons are positively charged particles and neutrons does not posess any charge.
3. Neutrons and protons togather are known as neutrons.
(B) Protons
1. Protons are positively charged particles.
2. Magnitude of charge on a proton is +1.6x10^-19 C.
3. Mass of a proton is 1841 times greater then that of an electron.
4. Total number of protons in a atomic nucleus (Z-atomic number) is equal to the number of electrons in the neutral atom.
(c) Neutron
1. Neutron is a chargeless particle.
2. Mass of a neutron is aproximately equal to the mass of a proton.
3. The number of protons plus the number of neutrons in the nucleus is known as mass number of the nucleus.
(D) Definations
1. Nuclide:- A single nuclear species (single value of both Z and N ) is called nuclide and it is represented as _ZX^A.
2. Isotopes:- Nuclides having same number of protons but different number of neutrons.
3. Isobars:- Nuclides having same number of nucleons but different number of protons.
4. Isotones:- Nuclides having same number of neutrons but different number of protons.
(E) Properties of nucleus
1. The radius of nucleus is of the order of 10^-15.
2. Radius of nuclei is represented by the relation
R=R₀A^1/3
where R₀=1.2x10^-15 is a constant same for all the nuclei.
3. Volume of the nuclei is proportional to A.
4. Density of nuclei is very high about 10¹² times greater then that of lead.
5. Nucleus also posess angular momentum and magnetic moment which arises as a result of continous motion of neutrons and protons inside the atomic nucleus.

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