Write down the electronic configuration of elements from atomic number 21 to atomic number 30. Also name the elements.

How will you account for the electronic configuration of the elements with atomic number of 24 and 29?
Or
Account for the following:
The continuous building up of 3d subshell interpreted in chromium (At. No. 24) and copper (At No. 29).
Or
Outer electronic configuration of chromium is 3d⁵ 4s¹ and not 3d⁴ 4s². Explain.

243. Indicate the number of unpaired electrons in:
(a) P, (b) Si, (c) Cr, (d) Fe and (c) Kr. 

Write the electronic configurations of the following ions: (a)H^- (b) Na⁺ (c) O^2- (d) F^-

Which atoms are indicated by the following configurations?
(a) [He] 2s¹       
(b) [Ne] 3s² 3p³              
(c) [Ar] 4s² 3d¹. 

Which of the following are isoelectronic species, i.e. those having the same number of electrons?

Na⁺, K⁺ , Mg²⁺, Ca²⁺, S^2-, Ar. 

What is the cause of greater stability of exactly half-filled and completely filled configurations?

An atom of an element contains 29 electrons and 35 Deutrons. Deduce (i) the number of protons and (ii) the electronic configuration of the element.

Write the electronic configurations of the following ions/atom:
(i) Cu²⁺              (ii) Cr³⁺
(iii) Ni²⁺                  (iv) Rubidium (Z = 37)