How Valency is calculated for an element?

Calculate the valency of an element using the total number of electrons. The valency of an atom is equal to the number of electrons in the outer shell if that number is four or less. Otherwise, the valency is equal to eight minus the number of electrons in the outer shell. read more

Valency of an atom is the number electrons in the outer most shell or valency is the number of eight minus the number of electrons the outer most shell.If one know the number of electrons then easily calculate the valency.Except hydrogen all other atoms have 2 electrons in inner most shell and up to eight electrons in the remaining shells ,for example if chlorine have atomic number 17 and its electronic configuration is 2,8,7. read more

It's also possible to calculate the valency of an atom or molecule by noting how it combines with other atoms or molecules with known valencies. The Octet Rule When determining the valency of an atom or molecule (one for which you can't use the periodic table to determine valency), chemists use the octet rule. read more

You should know the valency of the elements or the ions to write the chemical formula of a compound , Chlorine has a valency of 1 as it needs to gain 1 electron to achieve noble gas electronic configuration . read more