Practice Questions

Define transition elements according to the IUPAC definition.

Identify the element in the 3d series that exhibits the largest number of oxidation states.

Name the oxometal anion of manganese where the metal is in its highest oxidation state (+7).

List four general characteristic properties of transition elements.

Name the two series of inner transition elements.

Justify why a transition metal exhibits its highest oxidation state in its compounds with oxygen and fluorine.

Justify why an aqueous solution of $Zn^{2+}$ ions is colourless.

Manganese ($Z=25$) is known to exhibit the largest number of oxidation states among the first-row transition elements. Justify this observation based on its electronic configuration.

Recall the formula used to calculate the 'spin-only' magnetic moment and its unit.

Examine the primary reasons why transition metals are known for forming a large number of complex compounds.

Analyze why transition metals exhibit high enthalpies of atomisation.

Apply the concept of orbital stability to explain the anomalous electronic configurations of Chromium ($Z=24$) and Copper ($Z=29$).

Define 'lanthanoid contraction' and name one of its major consequences.

Explain why Zinc ($Z=30$) is not regarded as a transition element.

Describe why most transition metal ions are coloured, whereas ions of s-block and p-block elements are generally colourless.

Recall the anomalous electronic configurations of Chromium ($Cr, Z=24$) and Copper ($Cu, Z=29$) in the 3d series.

Define interstitial compounds and list two of their properties.

Explain the interconversion of chromate ($CrO_4^{2-}$) and dichromate ($Cr_2O_7^{2-}$) ions in aqueous solution.

Describe the key differences between lanthanoids and actinoids regarding their oxidation states and chemical reactivity.

Calculate the 'spin-only' magnetic moment for the $\text{Fe}^{2+}$ ion in Bohr Magnetons (BM). The atomic number of Iron (Fe) is 26.

Analyze why Zinc (Zn), Cadmium (Cd), and Mercury (Hg) are generally not considered as transition metals, even though they belong to the d-block of the periodic table.

Calculate the 'spin-only' magnetic moment for a divalent ion of an element with atomic number $Z = 27$.

Demonstrate how the formation of colored ions by transition elements can be explained using the concept of d-d transition, with $\text{Ti}^{3+}_{(\text{aq})}$ as an example.

Contrast the chemical reactivity and oxidation states of lanthanoids with those of actinoids.

Analyze the interconversion of chromate and dichromate ions in an aqueous solution as the pH is altered. Provide the balanced ionic equations for the reactions.

Formulate a justification for the anomalous electronic configurations of Chromium ($Z=24$) and Copper ($Z=29$), evaluating the energetic factors that favour these configurations over the expected ones.

Evaluate the trend in enthalpies of atomisation across the 3d transition series and justify why Zinc has the lowest value ($126 \text{ kJ mol}^{-1}$).

Critique the statement: 'The first ionisation enthalpy of the 3d transition elements increases regularly across the series.' Justify your position with specific examples.

Evaluate the characteristic properties of interstitial compounds formed by transition metals, such as high melting points and chemical inertness, and propose a structural reason for them.

Critique the statement 'The chemistry of actinoids is very similar to that of lanthanoids.' Justify your answer by comparing their range of oxidation states and chemical reactivity.

Propose a method to determine the number of unpaired electrons in a $Co^{2+}$ ion. Calculate its 'spin-only' magnetic moment and justify why experimental values might differ from the calculated value.

Formulate the balanced ionic equations for the oxidation of (i) iron(II) ions and (ii) oxalate ions by acidified potassium permanganate ($KMnO_4$). Justify the essential role of the acidic medium.

Actinoid contraction is greater from element to element than lanthanoid contraction. Propose a reason for this observation based on the nature of f-orbitals.

Propose a detailed explanation for the phenomenon of Lanthanoid contraction and evaluate its primary consequences on the properties of the 5d series elements.

Analyze why the $\text{Cu}^+$ ion is not stable in aqueous solutions and tends to undergo disproportionation.

Summarize the preparation of potassium dichromate ($K_2Cr_2O_7$) from chromite ore ($FeCr_2O_4$).

Examine the redox reaction that occurs when acidified potassium permanganate solution is added to an aqueous solution of ferrous sulfate. Write the balanced ionic equation and identify the oxidizing and reducing agents.

Evaluate the standard electrode potentials ($E^{\circ}$) for the $M^{2+}/M$ couple of Manganese, Nickel, and Zinc. Justify why their values are more negative than expected from the general trend across the 3d series.

Analyze the trends in the first and second ionization enthalpies of Chromium ($Z=24$) and Zinc ($Z=30$).

Apply your knowledge of standard electrode potentials to analyze which ion, $\text{Cr}^{2+}$ or $\text{Fe}^{2+}$, is a stronger reducing agent and why. Given: $E^\circ_{\text{Cr}^{3+}/\text{Cr}^{2+}} = -0.41 \text{ V}$ and $E^\circ_{\text{Fe}^{3+}/\text{Fe}^{2+}} = +0.77 \text{ V}$.

Compare the atomic radii of the elements in the second (4d) and third (5d) transition series. Analyze the reason for the observed trend.

Compare the ability of oxygen and fluorine to stabilize the highest oxidation states of transition metals. Analyze why oxygen is sometimes superior in this regard.

Critique the IUPAC definition of a transition metal by evaluating why Zinc ($Z=30$) is not considered one, while Silver ($Z=47$) is, despite both having a completely filled d-orbital in their ground state.

Explain why the enthalpies of atomisation of transition metals are high.

Design an experimental outline to demonstrate the catalytic activity of iron(III) ions in the reaction between iodide ions ($I^−$) and persulphate ions ($S_2O_8^{2−}$). Propose a plausible two-step mechanism for this catalysis.