Question

An element has its electronic configuration as 2,8,2. Now answer the following questions according to modrn periodic table.
a. What is the atomic number of this element?
b. What is the group of this element?
c. To which period does this element belong?
d. With which of the following elements would this element resemble?
(Atomic numbers are given in the brackets)
N (7), Be (4) , Ar (18), Cl (17)

Answer 1

a. Atomic number of the element is equal to the total number of protons present in it. Number of electrons is equal to number of protons in an atom. In the given element:
Total number of protons = 2 + 8 + 2= 12

b. The number of electrons present in the outermost shell of the element is 2. This means its valency is 2.
Thus, it belongs to the group 2.

c. The element belongs to period 3 because it has total 3 shells (2,8,2). The number of shells tell the period number of the element.

d. The electronic configuration of Be is 2,2. The number of electrons present in the outermost shell is 2. Thus, Be belongs to the group 2. The given element also belongs to group 2.
Thus, Beryllium (Be) resembles the given element.