Question

Subshell electronic configurations of some

elements are given (Symbols are not real

(A) [Ne] 3s2 3p5

(B) [Ar ] 4s1

(C) [ Ar] 3d5 4s2

(D) [Ar] 3d10 4s2 4p5

(a) Which of these elements belongs to the

same group ?

(b) Which element has the lowest ionisation

energy

(c) Which is the element that always show +1

Oxidation State ?

(d) Write down the subshell electronic

Configuration of C4+ ion​

Answer 1

Answer:

The electron configuration of an atom shows the number of electrons in each sublevel in each energy level of the ground state atom.

Here, 1s

2

2s

2

2p

6

3s

2

3p

2

3d

5

4s

1

is ground state electronic configuration of Cr.

Note: To write the electronic configuration a more convenient way is shown in figure below.

solution

Explanation:

(a) The electronic configuration of the element R is wrongly given. This is because the electron filling in the subsequent sub-shell will take place only after filling 6 electrons in the 3p sub-shell.

(b) Element Q has the highest electronegativity.

(c) P and Q can join to form an ionic compound. There is only one electron (4s

1

) in the outermost shell of the element P. So, it can easily donate that electron to Q. Q can accept that electron as it has only 7 electrons in the outermost shell and attain the octet form. Thus, an ionic compound PQ is formed by the transfer of electrons.