Describe and explain the differences in density and melting point between cobalt and calcium.
Transition metals may form complexes. What is meant by the term transition metal complex?
Cobalt can form the compounds $[\text{Co(NH}_3)_5\text{Br}]\text{SO}_4$ and $[\text{Co(NH}_3)_5\text{SO}_4]\text{Br}$. These two compounds are structural isomers. Define the term structural isomer.
Draw a three-dimensional diagram to show the structure of the ion $[\text{Co(NH}_3)_5\text{Br}]^{2+}$. Name its shape.
State the type of bonding between the cobalt ion and NH$_3$ groups in the $[\text{Co(NH}_3)_5\text{Br}]^{2+}$ ion.
State the oxidation number of cobalt in: • $[\text{Co(NH}_3)_5\text{Br}]^{2+}$ • $[\text{Co(NH}_3)_5\text{SO}_4]^+$
The solutions of $[\text{Co(NH}_3)_5\text{Br}]\text{SO}_4$ and $[\text{Co(NH}_3)_5\text{SO}_4]\text{Br}$ can be told apart by simple chemical tests. Complete the table with two different tests that could be used to identify each compound positively. Give the expected observation for each compound.
The two compounds $[\text{Co(NH}_3)_5\text{Br}]\text{SO}_4$ and $[\text{Co(NH}_3)_5\text{SO}_4]\text{Br}$ have different colours. Explain why the colours of the two compounds are different.
Some transition metals and their compounds act as catalysts. Catalysis can be grouped as heterogeneous or homogeneous. Complete the table by placing one tick (✓) in each row to show the type of catalysis in each reaction: • Fe in the Haber process • Fe$^{2+}$ in the I$^-$/S$_2$O$_8^{2-}$ reaction • NO$_2$ in the oxidation of SO$_2$ • V$_2$O$_5$ in the Contact process