Definition of Transition Element
Transition metals are a group of elements found on the periodic table in the central region. Most metals are found within this group. These metals have high melting points and high densities. Chemistry tutors often start this topic by explaining the term given to this group in Chemistry tuition. This group is termed as ‘transition’ is due to these metals exhibiting transitional behaviour between the s-block and p-block elements of the periodic table. These elements have an incomplete d-sub-level in one or more of their oxidation states. For instance, Zinc is not a transition metal as it has a complete d sub-level in all its oxidation states. Transition metals exhibit various properties, including variable oxidation states, having coloured compounds, and displaying catalytic and magnetic properties.
Variable Oxidation States
Transition metals exhibit variable oxidation states as their 3d and 4s sub-levels are very similar in energy levels. As such, both energy sub-levels can be used for bond formation, resulting in the element’s variable oxidation states.
Transition Metals as Catalysts
Chemistry tutors will also reveal in Chemistry tuition how the commonly known catalysts in chemical reactions, often are formed from these transition metals. Catalysts lower the activation energy required for the chemical reaction, thus increasing its rate. Transition metals are often used in industrial processes as catalysts. Chemistry tutors will often rely on real-life examples to help students understand its uses. For instance, transition metals are used in the production of ammonia and sulfuric acid. Another common example would be the use of palladium in a car’s catalytic convertors. Students in Chemistry tuition tend to rely on these applications when internalising complex concepts, thus assisting their learning.
Magnetism and Transition Metals
Transition metals also exhibit magnetic properties because there are unpaired electrons in the (n-1) d-orbital. Chemistry tutors will highlight key elements, such as Iron, that exhibit permanent magnetism, also known as ferromagnetism. This occurs as the unpaired elections align parallel to each other in domains irrespective of whether an external magnetic electric field is present. In Chemistry tuition, students will learn for instance, that this is how compasses are formed, that align with the Earth’s magnetic field.
How Transition Metal complexes exhibit Colour
Transition metal ions form complexes with other molecules, and in doing so form coloured compounds. This occurs as electrons are able to move from the lower energy d-orbitals to the higher energy d-orbitals by absorbing a photon of light. The wavelength of light absorbed by the electrons is dependent on the size of the energy gap between the two d-orbitals. When light is passed through the solution, and the colours that are not absorbed, the resulting colour will be reflected. For instance, when light is shone through copper(II) sulfate solution, the copper ions absorb light in the red region of the spectrum, and the remaining colours pass through unabsorbed, thereby resulting in a pale-blue coloured solution.
Students seeking Chemistry tuition will often find themselves enjoying this topic. Chemistry tutors often use incorporate creative methods to teach this topic early on in the year.
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