Home / AS & A Level Chemistry 10.1 Similarities and trends in the properties of the Group 2 metals Exam Style Practice Questions Paper 1
Caesium and barium are in Period 6 of the Periodic Table.
Which row is correct?
| The larger ionic radius | The higher melting point | |
|---|---|---|
| A | \(\mathrm{Ba^{2+}}\) | barium |
| B | \(\mathrm{Ba^{2+}}\) | caesium |
| C | \(\mathrm{Cs^+}\) | barium |
| D | \(\mathrm{Cs^+}\) | caesium |
Correct Answer: \( \boxed{\mathrm{C}} \)
Both ions are isoelectronic with xenon, but \(\mathrm{Ba^{2+}}\) has a greater nuclear charge than \(\mathrm{Cs^+}\), so \(\mathrm{Ba^{2+}}\) has the smaller ionic radius.
Barium has a much higher melting point than caesium because it contributes two delocalised electrons per atom, giving stronger metallic bonding.
Therefore, the correct answer is (C).
Which row shows the trends in the named properties going down the Group 2 nitrates?
| Thermal stability | Volume of gas produced, measured at room conditions, when \(1.0\,\mathrm{g}\) of anhydrous solid nitrate is thermally decomposed | |
|---|---|---|
| A | increases | increases |
| B | increases | decreases |
| C | decreases | increases |
| D | decreases | decreases |
Correct Answer: \( \boxed{\mathrm{B}} \)
Down Group 2, the nitrates become more thermally stable because the larger cations have a lower polarising power.
As the relative formula mass increases, \(1.0\,\mathrm{g}\) of nitrate contains fewer moles, so fewer moles (and hence a smaller volume) of gaseous products are produced on decomposition.
Therefore, the correct answer is (B).
The trends seen in Group 2 can be used to predict the properties of radium and its compounds.
Which statement is correct?
Correct Answer: \( \boxed{\mathrm{D}} \)
Down Group 2:
Since radium is below barium in Group 2, it reacts with water more rapidly than the other Group 2 metals.
Therefore, the correct answer is (D).