13.1 First-row d-block elements
Written specifically for students to provide help and support for the IB Diploma chemistry programme this page provides full coverage of the syllabus content of Topic 13.1 First-row d-block elements. It encourages you to think critically and provides many questions with full worked answers so that you can monitor and improve your knowledge and understanding.
Learning outcomes
After studying this topic you should be able to:
Understand
- Transition metals have variable oxidation states, form complex ions with ligands, have coloured compounds, and display catalytic and magnetic properties.
- Transition metals have an incomplete d sub-level in one or more of their oxidation states so zinc is not considered to be a transition element as it does not form ions with incomplete d-orbitals.
- When ions are formed, the s electrons are lost first so transition metals all show an oxidation state of +2.
Apply your knowledge to:
- Explain the ability of transition metals to form variable oxidation states by considering successive ionization energies.
- Explain the nature of the coordinate bond within a complex ion.
- Deduce the total charge of a complex ion given the formula of the ion and ligands present. Explain the magnetic properties in transition metals in terms of unpaired electrons.
Relationships & vocabulary
Nature of science
Science looks for trends and the discrepancies within these trends. The behaviour of the transition elements follows certain patterns. The d-block elements zinc, chromium and copper do not always follow these patterns and so can be considered anomalous in the first-row d-block.
International-mindedness
Because of their properties and uses transition metals are important international commodities. For some countries, mining for precious metals is a major economic factor.
For examples and more links to International mindedness, Theory of knowledge, utilization etc. see separate page which covers all of Topics 3 & 13: Periodicity.
Vocabulary
| variable oxidation state (or number) | complex ion | ligand | monodentate |
| paramagnetism/paramagnetic | diamagnetism/diamagnetic | polydentate |
Learning slides
You can use this slide gallery for learning or for reviewing concepts and information. It covers all the key points in the syllabus for this sub-topic.
First row d-block elements:
First row d-block elements:
First row d-block elements:
First row d-block elements:
First row d-block elements:
First row d-block elements:
First row d-block elements:
First row d-block elements:
First row d-block elements:
Something to think about
Paramagnetism
The syllabus include the magnetic properties of transition metals. However if you are not careful it could be a case of ' a little knowledge is a dangerous thing'. Paramagnetism is associated with unpaired electrons as a spinning unpaired electron creates a small magnetic field. This will line up in an applied electric or magnetic field to make the transition metal complex weakly magnetic when the field is applied, i.e. they reinforce the external magnetic field. The more unpaired electrons there are in the complex ion the stronger will be the paramagnetic effect. It is tempting to ask questions such as; "Will Fe2+ complexes be paramagnetic?"
The electron configuration of iron is 1s22s22p63s23p64s23d6 so, when the two 4s electrons have been lost to form the ion, Fe2+ will have the configuration [Ar]3d6. In an octahedral complex the five d orbitals are split with three of them going to lower energy and two to higher energy. Applying the Aufbau principle of filling the lower energy orbitals first the six electrons will form three pairs of electrons in the lower three 3d orbitals and so the complex ion will exhibit no paramagnetism, i.e. it will be diamagnetic. This seems straightforward logic but it ignores the effect of the ligands and in particular their position in the spectrochemical series. Ligands high in the series such as CN¯ cause large splitting (see diagrams where ΔE' > ΔE) and the complex [Fe(CN)6]4¯ is indeed diamagnetic as it has no unpaired electrons. However when water is the ligand the splitting is much less and now it is energetically favourable to apply Hund's rules and the complex ion [Fe(H2O)6]2+ has four unpaired electrons and is consequently paramagnetic.
High and low spin complexes are not specifically on the syllabus but it does mean that if you are asked to deduce whether a compound will be paramagnetic or not it could cause unforeseen problems.
Test your understanding of this topic
(Note that your teacher may have restricted your access to some or all of these questions and worked answers if they are going to use them as a class test or set them as an assignment.)
For ten 'quiz' multiple choice questions with the answers explained see MC test: First-row d-block elements.
For short-answer questions see First row d-block elements questions.
More resources
1. Paramagnetism and diamagnetism in general explained well by the Department of Physics and Astronomy, UCLA
Paramagnetism and diamagnetism
2. A video by Flinn Scientific showing the strong paramagnetism of the Mn2+ ion which contains five unpaired electrons.
Paramagnetic transition metal ions
3. A catalytic converter deconstructed from the Science Channel. An excellent video showing how a catalytic converter works. It stresses the importance of both surface area and temperature for the efficient functioning of the platinum, rhodium and palladium catalysts.