Question

Subshell electronic configuration of some elements are given (Symbols are not real): A -1s² 2s² 2p⁴ , B -1s² 2s² 2p⁶ 3s¹ , C - 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ , D - 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² a) Find the atomic number of 'B'. *
12
1
11
8​

Answer 1

Answer:

(a) The correct electronic configuration of element A is:

1s

2

2s

2

2p

6

3s

2

3p

6

4s

1

(b) Fourth period.

(c) The electronic configuration of element A is

1s

2

2s

2

2p

6

3s

2

3p

6

4s

1

The electronic configuration of element C is

1s

2

2s

2

2p

6

3s

1

From the electronic configuration of the elements A and C, the atomic size of A is greater than the atomic size of C. Hence, the distance between the outermost electron of element A and its nucleus is more than the distance between the outermost electron and nucleus of element C. As the atomic size increases, the effective nuclear attraction experienced by the outermost electron decreases. Therefore, among the atoms A and C, the attraction of the nucleus towards the outermost electron is greater in case of element C.