11/12/2023 0 Comments Photo light pro transitions![]() ![]() Students can find it hard to fully explain why zinc compounds are colourless.The absorption of light will show complementary colours, eg a solution appears violet in colour because the solution absorbs yellow light, which is the complementary colour to violet. Learners can confuse absorption and emission.Electronic configurations with filling of d-orbitals, sub-shells and d−d transition of electrons can seem abstract to students.Explain to your students that it doesn’t mean complicated in this context, and refers to the compound consisting of multiple parts. A transition metal can exist in a range of oxidation states in its compounds, and can be readily inter-converted. The d-orbitals are no longer degenerate in a complex of a transition metal due to the repulsions of orbitals on particular axes with approaching ligands and a change in energy.The colours of most transition metal complexes are due to d−d electron transitions absorbing the complementary colour of light to what’s observed. The colour depends on the transition metal, oxidation state, ligands and coordination number. The coordination number of the complex is the total number of bonds from the ligands to the central transition metal. A ligand is an ion or molecule with a lone pair of electrons to donate to form a coordinate (dative covalent) bond with a transition metal ion. To understand transition metal ions and their complexes, students need to be secure in their grasp of detailed electronic arrangements and d-subshells. A transition metal complex consists of a central metal ion surrounded by ligands. ![]() ![]() Transition metal ions, surrounded by ligands coordinating to a central metal ion, have been used in medicine for decades – in applications such as anti-cancer treatments or as tracers providing diagnostic information.ĭ-orbitals, electrons and energy gaps can seem hugely abstract to students, so real-world contexts, and the wonderfully colourful chemistry of transition metal complexes – that they can actually see – offer a tangible route to learning the underlying chemistry. When deoxygenated, it is colourless when oxygenated, it’s blue. While the coordination of iron(III) is responsible for the red colour in haemoglobin, it is copper(II) that gives haemocyanin its blue colour. Why is blood red? Why, for some sea creatures, is blood blue? The answer lies in the fascinating and colourful topic of transition metal complexes. When teaching this topic, refer to the real-world context of Atlantic horseshoe crabs’ blue, copper-based blood called lysate ![]()
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