K+ ------- Number of protons =
19Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
Number of protons is equal to atomic number of an element.
            Â
Number of netrons = 39-19 =
20Â Â Â Â Â Â Â Â Â Â Â Â Â
Number of neutrons = mass number - atomic number
           Â
Number of electrons = 18 Number of electons is equal to atomic
number when the atom is neutral.
                                               Â
but for cation, subtract the charge and for anion , add the charge
to the atomic number.
Cl-Â Â Â Â Â Â Â Â Â =
number of protons = 17
                Â
= number of neutrons = 35.5-17 = 18.5
                 Â
= number of electrons = 18
C = number of protons = 6
   = number of neutrons = 12-6 =6
= number of electrons= 6.
