Question

What is the cause for placing calcium in IIA group of modern periodic table

Answer 1

Because calcium having valency 2 and also According to modern periodic table,there is a order for placing of electrons.so Ca was placed in 2a group

Answer 2

Explanation:

It is known that all the elements of group 2A tend to show valency of +2. As the atomic number of calcium is 20 and its electronic configuration is 2, 8, 8, 2.

And, in order to attain stability it loses two electrons and hence, acquires a general electronic configuration similar to alkaline earth metals that is, $ns^{2}$.

Therefore, calcium shows properties similar to the properties displayed by elements of group 2A.

Thus, we can conclude that 2 valence electrons is the cause for placing calcium in IIA group of modern periodic table.