Dear sir,how do we decide that which ion has a higher charge?i mean on which factors do the strength of charge of an atom depends? or How can we say that na+ has a higher nuclear charge than cl- ?(which factor is considered while deciding this)

Charge of an ion depends upon the number of electrons and protons.Protons have positive charge which reside in nucleus while electrons have negative charge which revolve around the nucleus in orbits.Whichever is greater, atom attains that charge.Na⁺ has positive chage which means that it has lost one electron while Cl^- has negative charge which means that it has gained one electron.But,both have one unit charge.