Difference Between D Block Elements and Transition Elements

Key Difference – D Block Elements vs Transition Elements
 

The difference between D-block elements and transition elements is quite confusing. Both words are used interchangeably, and many people use the word ‘transition elements’ for d-block elements. The key difference between D-block elements and transition elements is that while all transition elements are D-block elements, not all D-block elements are transition elements. It is clear that d-block elements have d-electrons in the d-sub shell. Transitions elements are the elements which form stable ions having incompletely filled d-orbitals. For example, Zinc and Scandium are d-block elements; but not transition elements.

What are D-block Elements?

D-block elements can be clearly identified using the electron configuration and the position of the periodic table. The main feature of d-block element is having at least one electron in the d-sub shell. The odd thing happens when the filling of electrons according to Aufbau principle in d-block elements is, 4s-electrons are first filled before 3d-electrons; which means 3d-elctrons have higher energy than 4s-electrons. But, when they remove electrons to form ions; 4s-electrons are first removed from the atom.

 Note:[Ar] = 1s²2s²2p⁶3s²3p⁶

What are Transition Elements?

Transition elements are the elements which form stable ions with incompletely filled d-orbitals.When ions are formed by d-block elements; they first eliminate the s-electrons (n-level) and then remove d-electrons (n-1 level).  Zinc and Scandium are two special elements in the d-block; they don’t form ions having incompletely filled d-orbitals; therefore they are not considered as transition elements. All the other elements in the d-group form stable ions whose having incompletely filled d-electrons.

What is the difference between D-block Elements and Transition Elements?

Definition of D-block Elements and Transition Elements

D-Block Elements: The elements having one or more d-electron in the d-sub shell are known as d-block elements. Most of the d-block elements are metals.

Transition Elements: The elements which can form stable ions with incompletely filled d-orbitals are called transition elements.

Note:

Zn and Sc are not transition elements. They don’t form only Zn²⁺and Sc³⁺ ions, which do not contain unfilled d-orbitals.

Zn²⁺ =1s²2s²2p⁶3s²3p⁶3d¹⁰

Sc³⁺=1s²2s²2p⁶3s²3p⁶3d¹⁰

The following ions contain unfilled d-orbitals.Therefore, these elements are considered as transition elements.

Cu²⁺ = 1s²2s²2p⁶3s²3p⁶3d⁹

Ni⁴⁺= 1s²2s²2p⁶3s²3p⁶3d⁶

Mn²⁺= 1s²2s²2p⁶3s²3p⁶3d⁵

Fe²⁺= 1s²2s²2p⁶3s²3p⁶3d⁶

Oxidation States:

D-Block Elements: Some of D-block elements show multiple oxidation states and few of them show a single oxidation state.

Example:

Zinc shows only +2 oxidation state and Scandium shows only +3 oxidation state.

Other elements in the d-block show multiple oxidation states.

Transition Elements: Transition elements show multiple oxidation states. At least one state contains unfilled d-orbitals.

Example:

Titanium                    +2, +4

Vanadium                  +2, +3, +4, +5

Chromium                 +2, +3, +6

Manganese               +2, +3, +4, +6, +7

Ferrous                       +2, +3

Cobalt                         +2, +3

Nickel                         +2, +4

Copper                        +1, +2

Image Courtesy:

1. “Periodic table blocks spdf (32 column)” by User:DePiep [CC BY-SA 3.0] via Commons

2. “Coloured-transition-metal-solutions” [Public Domain] via Commons