NJC 2026 Transition Elements Notes_Student

National Junior College SH2 H2 Chemistry 1 AN INTRODUCTION TO THE CHEMISTRY OF TRANSITION ELEMENTS Content • General physical and characteristic chemical properties of the first set of transition elements, scandium to copper • Colour of complexes Learning Outcomes Candidates should be able to: (a) explain that a transition element is a d block element whose atom has an incomplete d subshell, or which can give rise to cations with an incomplete d subshell (b) state the electronic configuration of a first row transition element and of its ions (c) explain why the atomic radii and first ionisation energies of the transition metal atoms are relatively invariant (d) contrast, qualitatively, the melting point and density of the transition elements with those of calcium as a typical s block element (e) describe the tendency of transition elements to have variable oxidation states (f) predict from a given electronic configuration, the likely oxidation states of a transition element (g) describe and explain the use of Fe 3+/Fe2+, MnO 4−/Mn2+ and Cr 2O72−/Cr3+ as examples of redox systems (see also REDOX AND ELECTROCHEMISTRY) (h) predict, using Eꝋ values, the likelihood of redox reactions (see also ELECTROCHEMISTRY) (i) define the terms ligand and complex as exemplified by the complexes of copper(II) ions with water, ammonia and chloride ions as ligands (including the transition metal complexes found in the Qualitative Analysis Notes) (j) explain qualitatively that ligand exchange may occur, as exemplified by the formation of the complexes in (i), including the colour changes involved, and CO/O2 exchange in haemoglobin (k) describe, using the shape and orientation of the d orbitals, the splitting of degenerate d orbitals into two energy levels in octahedral complexes (l) explain, in terms of d orbital splitting and d -d transition, why transition element complexes are usually coloured [knowledge of the relative order of ligand field strength is not required] (m) explain how some transition elements and/or their compounds can act as catalysts (see also REACTION KINETICS) Copyright © 2026 National Junior College All Rights Reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording or any other information storage and retrieval system, without prior permission in writing from the copyright owner.

National Junior College SH2 H2 Chemistry 2 Note: Ground state electronic configurations of Cr and Cu atom are [Ar] 3d5 4s1 and [Ar] 3d10 4s1 respectively 1 Introduction Success Criteria: • I know the definition of a transition element. • I can state the electronic configuration of a first row transition element and of its ions. A transition element is d block eleme