John F. connor, Content Marketing executive, MA, Minsk,Poland
Answered Feb 08, 2019
Variable valency is a term associated in science with how well two elements combine. Some elements combine easily and others combine in a difficult way and then there are many combinations that combine between easy and hard. Calcium is highly reactive, so it would seem that it combines fairly easily.
Therefore, calcium has a variable valency of positive two. This means that it can give up two electrons to form or combine with another element. This is because the configuration of electrons is two, eight, eight and two. In order to combine, elements must give up or lose electrons to other elements in order for them to come together. Even though calcium is reactive and can combine with other elements, this does not mean that they will combine with every element out there.
An element's valency can often, but not always, be determined by studying its position in the periodic table. Calcium is in the fourth energy level, in the second group on the periodic table.
It's atomic number is 20 and its electronic composition is 2,8,8,2. It has two valency electrons so is described as +2 Valency measures the reactivity of an atom or molecule. these are on the outer shell.
Calcium does not have variable valency. Variable valency is the capacity of an element to combine differently with other metals depending on the nature of the reaction. Only D block elements have variable valency.
All the shells are filled in calcium except the outer shell that has 2 electrons. Calcium can only donate the two electrons in its outer shell, making the valency of calcium is +2.
The electronic configuration of calcium is (2, 8, 8, 2). According to the octet rule, it can attain stability by losing the 2 electrons in its outer shell. Elements that are not in the D- block can only form one stable ion.