Question

The subshell electronic configuration of an element X is given (symbol is not real) 1S2 2S2 2P6 3S2 3P6 3d5 4S2 a) Which are the shells present in an atom of element X, having electrons? b) In which subshell, the last electron was added? c) The element forms coloured compounds. Give reason. d) Write down the subshell electronic configuration of X2+ ion​

Answer 1

Answer:

x was 25 wihich means manganese mg a one answer s shell,p shell,d shell i think 4 sub Shell i don't know 3rd one answer means 1s2 2s2 2p6 3s2 3p63d5 4s2 and I think 4p1

Answer 2

Ans.a)The shells present in an atom of element X, having electrons are K, L, M, and N.

Ans.b) In 3d subshell, the last electron was added.

Ans.c)The element forms coloured compounds because it is a transition element.

Ans.d) Subshell configuration of X²⁺ is 1s²2s²2p⁶3s²3p⁶3d⁵4s⁰.

Explanation:

• a) By the electronic configuration $1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{5} 4s^{2}$, we can see that there are 4 shells in which electrons are present (n = 1, 2, 3 & 4).

n = 1 is K shell

n = 2 is L shell

n = 3 is M shell

n = 4 is N shell

• b) According to Aufbau's Principle, the electrons occupy the orbitals in order of increasing energy.

1s< 2s < 2p < 3s < 3p < 4s < 3d

Since 4s orbital (empty) has lower energy than 3d orbital (empty), the last electron is added in 3d subshell.

• c) Due to the presence of half-filled 3d orbitals, it can be inferred that the element is a transition metal. Transition metal compounds often show colour because electronic transitions between different d orbitals of different energies take place. These transitions may execute by charge transfer (LMCT and MLCT) or by the d-d transition.
• d) In X²⁺ two electrons are lost from 4s orbital. This is because 4s orbital has higher energy than 3d orbital after filling of electrons. Thus, the electronic configuration becomes  $1s^{1} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{5} 4s^{0}$.