Question

atom and atomic theory of matter

Answer 1

Atom is the smallest unit of an matter which can't further distroyed it consist of a nucleus having + charge and e-s with negative charge revolving around them in a fixed circular orbit.

Answer 2

Democritus, a Greek philosopher is credited with being the first to name the small, discrete particles from which he believed all objects are made.

These are now called atoms. An atom has a nucleus and electrons which revolve around it, which has negative charge.

To pull away the electrons from an atom it requires energy. The shells in the atoms are also called as energy levels. The shell closest to the nucleus has a low energy level and as we go away the energy level increases. Thus if an electron jumps from higher energy level to a lower one then it emits energy in the form of photon (which is light).

Neils bohr gave this atomic theory. There are a specific number of electrons in each shell, given by the formula, $2n^{2}$ Where "n" is the serial number of the shell.