Question 5.
Write down the electronic configuration of the following elements from the given atomic numbers. Answer the following question with explanation.
1H, 7N, 20Ca, 16S, 4Be, 18Ar
Which of these elements belong to the second group?
Answer:
Electronic configuration:
⇒ The atomic number of hydrogen = 1
The electronic configuration of 1H = 1
⇒ The atomic number of nitrogen = 7
The electronic configuration of 7N = 2,5
⇒ The atomic number of calcium = 2
The electronic configuration of 20Ca = 2,8,8,2
⇒ The atomic number of sulphur = 16
The electronic configuration of 16S = 2,8,6
⇒ The atomic number of beryllium = 4
The electronic configuration of 4Be = 2,2
⇒ The atomic number of argon = 18
The electronic configuration of 18Ar = 2,8,8
Among the given elements, Ca and Be belong to second group. Because both has two electrons in the outermost shell. Thus, these two elements belong to second group.
