Q15 / 105 · NTA Abhyas (JEE Main) 2020 · Chemistry · d and f Block Elements

Four successive members of the first row transition elements are listed below with their atomic numbers. Which one of them is expected to have the highest third ionisation enthalpy ?

  • A
    Vanadium ( Z =  23 )
  • B
    Chromium ( Z = 24 )
  • Correct answer
    C
    Manganese ( Z = 25 )
  • D
    Iron ( Z = 26 )

Solution

V2+ (21)         [ Ar ]18 3d3 4s0

Cr2+ (22)       [ Ar ]18 3d4 4s0

Mn2+ (23)      [ Ar ]18 3d5 4s0

Fe2+ (24)      [ Ar ]18 3d5 4s1

To find ionization enthalpy we first see electronic configuration.
Then we see shell.
If shell are same then see charge.
Then see extra stability ( Half filled and fully filled ).

⇒ I.E 3 Mn > I.E 3 Fe > I.E 3 Cr > I.E 3 V

Hence, the correct answer is option: 'C'.

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