JEE Main & Advanced Physics Nuclear Physics And Radioactivity Nucleus

(1) Rutherford's \[\alpha -\]scattering experiment established that the mass of atom is concentrated with small positively charged region at the centre which is called 'nucleus'.

(2) The stability or instability of a particular nucleus is determined by the competition between the attractive nuclear force among the protons and neutrons and the repulsive electrical interactions among the protons. Unstable nuclei decay, transforming themselves spontaneously into other structure by a variety of decay processes.

(3) We could not survive without the \[3.90\times {{10}^{26}}\] watt output of one near by fusion reactor, our sun.

(4) Nuclei are made up of proton and neutron. The number of protons in a nucleus (called the atomic number or proton number) is represented by the symbol Z. The number of neutrons (neutron number) is represented by N. The total number of neutrons and protons in a nucleus is called it's mass number A so \[A=Z+N\].

(5) Neutrons and proton, when described collectively are called nucleons. A single nuclear species having specific values of both Z and N is called a nuclide.

(6) Nuclides are represented as \[_{Z}{{X}^{A}};\] where X denotes the chemical symbol of the element.