Solveeit Logo
Login

Question

Chemistry Question on Classification of elements & periodicity in properties

Element with atomic number 38 belongs to

A

IIA group and 5th period.

B

IIA group and 2nd period.

C

VA group and 2nd period.

D

IIIA group and 5th period.

Answer

IIA group and 5th period.

Explanation

Solution

The electronic configuration of atomic number 38 is X (38) 1s2, 2s2,2p6, 3s2, 3p6, 4s2, 3d10, 4p6, 5s2 or 1s2, 2s2,2p6, 3s2, 3p6, 3d10, 4s2,4p6, 5s2.

Therefore, the elementbelongs to the IIA group and 5th period. The element is strontium(Sr).

Alternate Approach 1 - The correct option is A) IIA group and 5th period.

The explanation for the correct answer:

Option A: IIAgroup and 5thperiod.

Electronic Configuration of the element with atomic number 38

38 X = 2, 8, 18, 8, 2

  1. To check the period of an element - count the number of shells in the configuration.
  2. To check the group - we can check the number of electrons in the valence shell.

From the above configuration,

  1. There is 5 shell in which the electronis filled. So, the element belongs to the 5th period.
  2. In the valence shell, only 2 electrons are present. So, the element belongs to group 2.