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]