STD X – MODERN PHYSICS – RADIOACTIVITY – EINSTEIN

Atomic structure:

Everything in the world is made up of atoms. The structure of the atom is what gives an element its chemical and physical properties.

Atoms are made up of three smaller particles:

Electrons
Protons.
Neutrons.

Radioactivity:

Radioactivity refers to the particles which are emitted from nuclei as a result of nuclear instability. The most common forms of radiation emitted have been traditionally classified as alpha, beta, and gamma radiation.
An atom consists of a nucleus at its centre, surrounded by electrons which are revolving in some specific stationary shells (or orbits).Electrons in different shells have different energy values. The maximum number of electrons in a shell of number n is given as 2n2.

The electron has a negative charge equal to – 1.6 x 10-19 C (or – e).

Its mass is 9.1 x 10-31 kg.