C
CraftExam
medium difficulty8 min

Position of d-Block Elements in the Periodic Table

d-block elements are elements in which the differentiating electron enters the d-subshell of the penultimate shell. They are placed between the s-block and p-block elements in the periodic table.

In one line: d-block is a place; transition behaviour needs incomplete d-orbitals.

Practice This Concept

Understand it

The d-block occupies groups 3 to 12. The first transition series is the 3d series from scandium to zinc. Transition elements are generally defined as elements that have partially filled d-orbitals in their atoms or common ions, so zinc, cadmium, and mercury are often treated carefully because their common +2 ions have completely filled d10 configurations.

Example

In the first transition series, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn are 3d-block elements. Fe is a typical transition element because Fe2+ and Fe3+ contain partially filled d-orbitals.

Rule to remember

Rule: d-block elements have differentiating electrons entering (n-1)d orbitals.

Transition-element check: atom or common ion should have an incomplete d-subshell.

See it worked out

Follow the example line by line, then use the same method on new questions.

Worked example

Identify whether Cu is a transition element.

  1. 1Cu has configuration [Ar] 3d10 4s1, and Cu2+ has 3d9 configuration.
  2. 2Since Cu2+ has an incomplete d-subshell, copper is considered a transition element.

Method you can reuse

Write the electronic configuration, remove ns electrons before (n-1)d electrons when forming cations, then check whether the resulting common ion has an incomplete d-subshell.

Check yourself

Answer the question in your head before opening the answer.

Try it yourself

Why is iron considered a transition element while zinc is usually not considered a typical transition element?

Think first, then show answer
Iron forms ions such as Fe2+ and Fe3+ with partially filled d-orbitals, while Zn2+ has a completely filled 3d10 configuration, so zinc lacks many typical transition properties.

Common wrong answer

A common wrong answer is saying Zn is a typical transition element only because it is in the d-block, ignoring the d10 configuration of Zn2+.

Don't mix this up

Students often call every d-block element a transition element without checking whether the atom or its common ion has a partially filled d-subshell. Zn is d-block, but Zn2+ is d10 and does not show many typical transition properties.

Exam tip

For classification questions, first identify the block by the subshell receiving the differentiating electron, then decide whether it is a transition element by checking partial d-orbital occupancy in the atom or common ion.

Write it in the exam

Each point is worth about one mark. Write point 1 for a 1-mark question and keep adding points as the marks go up.

How CBSE asks it

Questions usually ask students to define transition elements, locate the 3d series, or explain why Zn, Cd, and Hg are not typical transition elements.
  1. 1

    Enough for 1 mark

    d-block elements are elements in which the differentiating electron enters the d-subshell of the penultimate shell. They are placed between the s-block and p-block elements in the periodic table.

  2. 2

    Add for 2 marks

    Example: In the first transition series, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn are 3d-block elements. Fe is a typical transition element because Fe2+ and Fe3+ contain partially filled d-orbitals.

  3. 3

    Add for 3 marks

    The d-block occupies groups 3 to 12.

MCQ Quiz

Practice this concept with focused MCQs

Open the concept quiz intro first, review the test details, and then start a focused MCQ set from this concept only. Instant score and answer review are live now.

10 MCQs5 MinutesInstant Results
Practice This Concept

Help improve this page

Found something confusing, incorrect, or missing?

Practice This Concept