Question

Total number of degenerate orbitals in the third orbital iof he+ ion is

Answer 1

It has 5 degenerate orbitals.

Just in case you want to know how they are calculated -

It is calculated on the basis of QUANTUM numbers.
There are 4 quantum numbers associated with every electron in an orbitals they are

1. Principle quantum number(n)
2. Azimuthal quantum number(l)
3. Magnetic quantum number
4. Spin quantum number
To calculate number of orbitals you must know the following data
The azimuthal quantum number(l) of
S subshell is 0
p-1
d-2
f-3
The total no of orbitals equal to total no of magnetic quantum numbers a subshell can possess.

The total no of magnetic no a subshell can possess is given by total nos from -l to +l or mathematically 2l+1.
Therefore since d orbital has l=2 it has magnetic quantum nos
-2 ,-1,0,1,2 total = 5
Hence it has 5 degenerate orbitals.

Answer 2

The total number of degenerate orbitals in the third orbital of the he+ ion is 9.

• The atomic number of helium is 2 and the electronic configuration of helium is 1s².
• He+ will be its first excited state and He will be its ground state.
• In He+ the electronic configuration is (1s0 2s1)
• Other configuration of He+ in its first excited state are (1s0 2px1) or (1s0 2py1) or (1s0 2pz1).
• Hence total degeneracy is 4.

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