(a) The cause of chemical combination between atoms of the various elements is their tendency to acquire nearest stable noble gas configuration of octet of electrons and gas duplet of election in case of hydrogen atoms in their outermost shells.
(b) An atom of hydrogen has one proton in its nucleus and one electron in its valence electron, the residual ion consists of a single proton. It is on account of this fact that hydrogen ion is called proton.
(c) In the formation of a cation, the atom loses the electrons of its outermost shell. Thus, the cation has one electron less than the smaller than the atom.
