d and f BLOCK ELEMENTS

Why is the standard electrode potential (E°) for the Fe²⁺/Fe couple less negative than that for Cr²⁺/Cr?

• Fe has lower ionization energies than Cr
• Cr²⁺ is more stable than Fe²⁺
• The higher (less negative) hydration enthalpy of Fe²⁺ compared to Cr²⁺ contributes to Fe's less negative E°
• Fe has a higher atomic number than Cr

Based on the information about halides, which of the following compounds would you expect to be the most covalent in nature?

• MnF₂
• FeF₃
• CoF₂
• VF₅

What is the significance of the statement "beyond Mn no metal has a trihalide except FeX₃ and CoF₃" in understanding 3d metal chemistry?

• It shows that trihalides are very common
• It indicates that +3 is the most stable state for all 3d metals
• It highlights a general decrease in the stability of the +3 oxidation state for 3d metals as the atomic number increases beyond Manganese
• It proves that fluorine only bonds with Cobalt

According to the provided data, which first-row transition metal has the lowest first ionization enthalpy (Δ₁H°)?

• Ti
• Cr
• Mn
• Zn

Why does the text mention the hydrolysis of VCl₅, VBr₅, and VI₅ to form oxohalides like VOCl₃?

• To show that VF₅ is unstable
• To prove that all V halides are stable
• To illustrate that high oxidation state halides (except fluorides) tend to be unstable and undergo hydrolysis
• To compare the bond strengths of V-F and V-Cl