Ionisation energies and shells |
1) a) Define the 1st ionisation energy and write the equation for Bromine [4]
The energy required to remove one electron from each atom [1] in 1 mole of gaseous atoms [1] to form 1 mole of gaseous 1+ ions [1]
Br(g) à Br+(g) + e- [1]
b) Write equations including state symbols to represent the:
i) 1st ionisation energy of Li Li(g) à Li+(g) + e- [1]
ii) 3rd ionisation energy of Al Al2+ (g) à Al3+(g) + e- [1]
Use the symbol e- to represent electrons [2]
c) What would you notice about the next ionisation energy for (i) and (ii)? Explain your answer using atomic structure. [7]
i) 2nd ionisation energy of Li would have a significant increase as you move to an inner electron shell. [1]
Due to less shielding [1] as fewer inner shells, electron is closer to the nucleus so greater attraction [1]
ii) 3rd ionisation energy of Al would show a slight increase as electron is removed from the same electron shell. [1]
Due to higher proton : electron ratio [1] increasing attraction of remaining electrons [1]. Shielding is the same. [1]
2) How does the 1st ionisation energy change down group 2 and explain why? [3]
As you go down a Group, the outer electron shell is further from the nucleus - attraction decreases. [1]
The more inner shells the greater the shielding. [1]
As you go down Group 2, ionisation energy decreases. [1]
3) Sketch the graph for the successive ionisation energies for Na [3]
Large jump between 1st and 2nd [1] general increase for 2 - 9 [1] large jump between 9 and 10 [1]
4) The successive ionisation energies are shown:
1 |
2 |
3 |
4 |
5 |
1086 |
2353 |
4621 |
6223 |
37832 |
a) To which group of the periodic table does this element belong? Explain your answer. [2]
Group 4 [1] as there is a large jump between IE 4 and 5 [1]
b) This element is in Period 2, identify the element. Explain your answer. [3]
Carbon [1] as it is in Group 4 from the large jump between IE 4 and 5 [1] Group 4 element in Gp2 is carbon [1]