Explain briefly how +2 state becomes mor | Class 12 Chemistry Chapter The d-and f-Block Elements, The d-and f-Block Elements NCERT Solutions

Question:

Explain briefly how +2 state becomes more and more stable in the first half of the first row transition elements with increasing atomic number?

Answer:

The oxidation states displayed by the first half of the first row of transition metals are given in the table below. 

  Sc Ti V Cr Mn
    +2 +2 +2 +2
  +3 +3 +3 +3 +3
Oxidation state   +4 +4 +4 +4
      +5 +5 +6
        +6 +7

It can be easily observed that except Sc, all others metals display +2 oxidation state. Also, on moving from Sc to Mn, the atomic number increases from 21 to 25. This means the number of electrons in the 3d-orbital also increases from 1 to 5.

Sc (+2) = d1

Ti (+2) = d2

V (+2) = d3

Cr (+2) = d4

Mn (+2) = d5

+2 oxidation state is attained by the loss of the two 4 selectrons by these metals. Since the number of d electrons in (+2) state also increases from Ti(+2) to Mn(+2), the stability of +2 state increases (as d-orbital is becoming more and more half-filled). Mn (+2) has d5 electrons (that is half-filled d shell, which is highly stable).


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Comments

  • Nihal Singh
  • 2018-09-18 08:27:02

Most stable element of lanthanide 2+


Comment(s) on this Question

Welcome to the NCERT Solutions for Class 12 Chemistry - Chapter . This page offers a step-by-step solution to the specific question from Excercise 2 , Question 3: Explain briefly how +2 state becomes more and more stable in the first half of the first row transit....