Valency of Calcium element is 2.

Calcium is an element with atomic number 20 and symbol Ca. It belongs to the alkaline earth metal group in the periodic table. The valency of an element refers to its combining power with other elements to form compounds. It represents the number of electrons an atom can gain, lose, or share to achieve a stable electron configuration.

Understanding valency:
Valency is determined by the number of valence electrons in an atom. Valence electrons are the electrons present in the outermost energy level or shell of an atom. The electronic configuration of calcium is 2, 8, 8, 2, where the outermost shell contains 2 electrons.

Calcium's valency:
To attain a stable electron configuration, calcium tends to lose its two valence electrons. By losing these electrons, it achieves a stable noble gas configuration similar to argon. The loss of two electrons results in the formation of a Ca2+ ion, which has a positive charge due to the loss of negatively charged electrons.

Calcium's compounds:
Calcium forms compounds by combining with other elements. Since it loses two electrons, it can combine with two negatively charged ions or one negatively charged ion with a valency of 2. This gives rise to compounds like calcium oxide (CaO), calcium chloride (CaCl2), and calcium carbonate (CaCO3).

Conclusion:
The valency of calcium is 2 because it readily loses its two valence electrons to achieve a stable electron configuration and form compounds by combining with negatively charged ions.