Question

What is meant by Radioactivity?

Answer 1

Radioactivity is a property which is exhibited by certain types of matter , emitting energy and subatomic particles spontaneously . It is an attribute of individual atomic nuclei. Radioactivity decay is a property shown by several naturally occurring elements as well as of artificially produced isotopes of the elements.

Complete step by step answer:
The nature of Radioactive emissions:- The emissary of the most common forms of spontaneous radio-active decay of are the alpha $\left( \alpha \right)$ particle, the beta $\left( \beta \right)$ particle, the gamma $\left( \gamma \right)$ ray, and the neutrino. The alpha particle is actually the nucleus of a helium- $4$ atom, with two positive charges ${_2^4}He$ . Such charged atoms are called Ions.
The neutral Helium atom has two electrons outside its nucleus balancing these two charges.
Beta particles may be negatively charged (beta minus, symbol, ${e^ - }$ ) or positively charged (beta plus, symbol ${e^ + }$ ).
The $\left[ {{\beta ^ - }} \right]$ beta minus particle is actually an electron created in the nucleus during beta decay without any relationship to the orbital electron cloud of the atom.
The beta plus particle, also called the positron, is the antiparticle of the electron. When brought together, two such particles will mutually annihilate each other.
Gamma rays are electromagnetic radiations such as radio waves, light and $X$ -rays. Beta radioactivity also produces the neutrino and antineutrino, particles that have no charge and very little mass, symbolized by $\upsilon$ and $\bar \upsilon$ , respectively.

Note: Nuclides are associated with radioactive decay and they can be stable or unstable species. In the world about $1,700$ nuclides are known of which about $300$ are stable and the rest are radioactive. More than $200$ of the stable nuclides were discovered by the British Physicist Francis William Aston using his new invention of the mass spectrograph.