A committee is a group of persons taken, elected or selected from the entire organisation to do some assigned work collectively. There are various types of committees divided on the basis of time, function, character and structure.
According to the Bohr’s atomic model, the electrons revolve around the nucleus in certain orbits. These electrons are distributed in various orbits according to a scheme proposed by Bohr and Bury.
The electronic configuration of an element is defined as follows: A stepwise distribution of electrons in different orbits (energy levels) of an atom is called its electronic configuration. To write the electric configuration of an element, one should proceed as follows.
The electronic configuration of an element gives an idea about its reactivity. The elements having a completely filled outermost orbit (or shell) will be chemically inert (non-reactive). For example, the outermost shell in the case of helium (He), neon (Ne) and argon (Ar) are completely filled as shown below.
Each element has a definite electronic configuration. The electrons in the outermost shell of an atom are termed as its valence electrons. The valence electrons take part in the chemical reactions.
Atoms are electrically neutral. A positive ion (or cation) is formed when an atom loses one or more electrons. An electron carries one unit of negative charge. So, the number of units of positive charge only a cation is equal to the number of electrons lost by the concerned atom.
The relative atomic mass is denoted by Ar. The relative atomic mass is a pure number, and hence it has been no unit.