Question

An atom of an element contains 35 electrons and 45 neutrons. Deduce
i) the number of protons
ii) the electronic configuration for the element
iii) All the four quantum numbers for the last electron

Answer 1

Given conditions ⇒

Numbers of the Electrons in an atom = 35 electrons.
Numbers of the Neutrons in an atoms = 45 neutrons.

 We know the numbers of the Electrons is always equals to the numbers of the Protons. 
(i)∴ Numbers of the Protons in an atom = 35.

(ii) Electronic Configuration of the Element is ⇒
By Bohr's bury method, 
E.C. = 2, 8.18, 7.

By Aufbau method, 

E.C. = 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁵

(iii) Quantum Numbers: Valence electron = 7

n = 4
ℓ = 1
mℓ = 0
ms = -1/2

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