Sodium and aluiminium have atomic numbers 11 and 13 respectively. They are sepearated by one element in the perodic table, and have valencies of one and three respectively. Chlorine and potassium are also separated by one element in the periodic table with atomic numbers 17 and 19 respecteively and yet both have the valencies of one. Explain the difference.



Yes there is difference in valencies of 17 and 19 because one is in positive and other is in negative ..between 17 and 19 noble gas present