Radioactivity

Radioactivity is the sending out of harmful radiation or particles, caused when atomic nuclei breakup spontaneously.

Radioactivity was discovered by Henry Becquerel, Madame Curie and Pierre Curie for which they jointly win Noble Prize.

The nucleus having protons 83 or more are unstable. They emit, α, β and γ particles and become stable. The elements of such nucleus re called radioactive elements and the phenomenon of emission of α, β and γ particles is called radioactivity.

Γ rays are emitted after the emission of α and β rays.

Robert Pierre and his wife Madame Curie discovered new radioactive element radium.

The rays emitted by radioactivity were first recognized by Rutherford.

The end product of all natural radioactive elements after emission of radioactive rays is lead.

Difference between stable and unstable nucleus

  

S.No.	Stable nucleus	Unstable nucleus
1	Low atomic number	High atomic number
2	Low mass number	High mass number
3	Nucleus of small size	Nucleus of bigger size
4.	n/p = 1	n/p> 1