Periodicity Practice Questions

Questions regarding ionisation energy

1: Why does Ne have a higher first ionisation energy than Ar ?

2: Why do first ionisation energies increase from Al to Si to P ?

3: Why is the first ionisation energy of Na much less than that of Ne ?

Questions regarding atomic radius

4: Explain why the radius of the atoms in Period 3 decreases across the period, even though the numbers of protons and neutrons increase.

Questions regarding melting and boiling points

5: The boiling points of sodium, magnesium and aluminium are 883ºC, 1107ºC, and 2467ºC respectively. Explain this trend.

6: Silicon and phosphorus are both covalently-bonded solid elements at room temperature. The melting point of silicon is 1410ºC while that of phosphorus is 44ºC.  Explain this difference.

7: The boiling points of the Period 2 elements nitrogen and fluorine are -195ºC and -188ºC respectively.  The corresponding elements in Period 3 do not show the same increase, phosphorus boils at 281ºC and chlorine at -35ºC.  Explain why this non-periodic behaviour occurs.

Other periodic properties – electrical conductivity

8: Which of the metals potassium or calcium has the greater electrical conductivity. Explain your answer.

9: Explain why the electrical conductivity of aluminium is much higher than than of silicon even though and aluminium atom as 3 outer-shell electrons and a silicon atom has 4 outer-shell electrons.

Check your answers