Cambridge International AS Level Chemistry
End-of-chapter questions
log10 ionisation energy
1 The sketch graph shows the 13 successive ionisation energies of aluminium.
0
a b c d
0
1 2
3 4 5 6 7 8 9 10 11 12 13 Number of electrons removed
Define the term 1st ionisation energy. How does the graph provide evidence for the existence of three electron shells in an aluminium atom? Write an equation, including state symbols, to represent the 2nd ionisation energy of aluminium. Write the electronic configuration of an aluminium ion, Al3+, using 1s2 notation.
[3] [6] [2] [1] Total = 12
2 The table below shows the 1st ionisation energies, ∆Hi1, in kJ mol–1, of the elements in Period 3 of the Periodic Table. 44
Element
Na
Mg
Al
Si
P
S
Cl
Ar
∆Hi1
494
736
577
786
1060
1000
1260
1520
a b c d
Explain why there is a general increase in the value of ∆Hi1 across the period. Explain why aluminium has a lower value of ∆Hi1 than magnesium. Write the electronic configuration for argon (Z = 18) using 1s2 notation. Copy and complete the diagram below for the 15 electrons in phosphorus by i adding labels for the other subshells ii showing how the electrons are arranged.
[4] [4] [1] [1] [3]
1s
e Predict a value for the 1st ionisation energy for potassium, which has one more proton than argon.
[1] Total = 14