Question

which of the following atoms is diamagnetic in its ground state? Cu As none of these Ca Fe

Answer 1

cu = atomic number =29 electronic configuration [ 1S2 2S2 2P6 3S2 3P6 4S1 3d10] although it consists of lone electron but it is diamagnetic

As = atomic number =33 electronic configuration [ 1S2 2S2 2P6 3S2 3P6 4S2 3d10 4p3] three unpaired electrons so para magnetic

Ca = atomic number = 20 electronic configuration [ 1S2 2S2 2P6 3S2 3P6 4S2 ] it is diamagnetic because of metallic nature

Fe = atomic number = 26 electronic configuration [ 1S2 2S2 2P6 3S2 3P6 4S2 3d6 ] it is a ferro magnetic (spins are aligned anti parallel )

answer => cu

Answer 2

To determine which atom is diamagnetic in its ground state, we need to understand that diamagnetic atoms have all their electrons paired up (no unpaired electrons).

Let's check each option:

1. Cu (Copper):

• Atomic number: 29

• Electron configuration: [Ar] 4s¹ 3d¹⁰

• The 4s electron is unpaired, so paramagnetic.

• 
  

2. As (Arsenic):

• Atomic number: 33

• Electron configuration: [Ar] 4s² 3d¹⁰ 4p³

• The 4p subshell has 3 unpaired electrons, so paramagnetic.

• 
  

3. Ca (Calcium):

• Atomic number: 20

• Electron configuration: [Ar] 4s²

• All electrons are paired, so diamagnetic.

• 
  

4. Fe (Iron):

• Atomic number: 26

• Electron configuration: [Ar] 4s² 3d⁶

• The 3d subshell has unpaired electrons, so paramagnetic.

• 
  

Answer is :-

Calcium (Ca) is the only diamagnetic atom in this list because all its electrons are paired.