Mod 2A: Electrons Test answers
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1)
This question is about two elements, A and B, in the periodic table.
a)
i)
Each atom of element A has 15 electrons.
Identify element A. [1]
Phosphorous
Complete the electronic configuration of A. [1]
ii)
1s2 2s2 2p6 3s2 3p3
iii)
Predict the charge on an ion of A and complete its electronic configuration. [2]
Charge on ion __3-___
electronic configuration of ion of A 1s2 2s2 2p6 3s2 3p6
Allow transferred errors from charge to configuration.
b)
The atoms of element B have eight electrons in the 3d sub – shell. Identify element B.
[1]
Ni
c)
How many orbitals does the 3d sub shell have?
d)
What is meant by the term orbital? [3]
It is a region within an atom that
hold up to 2 electrons with opposite spins
2)
The Group 7 element bromine was discovered in 1826. Bromine gets its name from
the Greek bromos meaning stench because of its strong smell.
a)
The electronic configuration of a bromine atom can be written in terms of sub – shells.
Complete the electronic configuration of a bromine atom. [2]
[1] 5
1s22s22p63s23p6 3d10 4s2 4p5 (2) 1 mark for p5 if incorrect
b)
3)
a)
Why is bromine classified as a p – block element? [1]
Outer electrons are in a p sub shell / orbital / shell
The first six ionisation energies of an element D are shown in the table.
1st
2nd
3rd
4th
5th
1086
2353
4621
6223
37832
6th
47278
Define the term first ionisation energy. [3]
The energy change when each atom in one mole (1) of gaseous atoms (1) Loses
an electron (1) to form one mole of gaseous 1+ ions.
Or
1 Mole of gaseous atoms loses 1 mole of electrons
3 marks
Or
D(g)

D+(g) +
e-
D(g)

D+(g) +
e-
2 marks
Or
H / IE = ….. KjMol-1
3 marks
b)
Write an equation, including state symbols, to represent the third ionisation energy of
element D. [2]
D2+(g) 
D3+(g) +
e-
(1) – equation
(1) – state symbols
Can use any example or letter instead of D, ‘-‘ not required on electron
c)
Use the table to deduce which group of the Periodic Table contains element D. [3]
Group ___4____
Explanation
Sharp rise in successive ionisation energy between 4th and 5th IE (1)
Which marks a change to a new shell / energy level / 4e in outer shell (1)
***Mention of – orbital / sub shell cancels mark 2.
This question is about aluminium oxide, Al2O3.
Successive ionisation energies provide evidence for the arrangement of electrons in
atoms. The graph below shows the 8 successive ionisation energies for oxygen.
Log ionisation energy
4)
a)
i)
2 3 4 5 6 7
Electrons removed
8
Write an equation, including state symbols, to represent the second ionisation energy
of oxygen. [2]
O+(g) 
ii)
1
O2+(g) +
e-
(1) – equation
(1) – state symbols
How does the graph provide evidence for the existence of two electron shells in
oxygen? [2]
Large difference between 6th and 7th IE (1)
Which marks a different shell (closer to the nucleus) (1)
iii) the O+ ion, is smaller than the O atom
OR
the electron repulsion/shielding is smaller
OR
the proton : electron ratio in the 2+ ion is greater than in
the 1+ ion
ALLOW the outer electrons in an O+ ion are closer to the nucleus
than an O atom
DO NOT ALLOW ‘removed from next shell down’
1
b)i)
Complete the electronic configuration for an aluminium atom. [1]
1s2 2s2 2p6 3s2 3p1
ii)
Sketch a graph to show the thirteen successive ionisation energies of aluminium. [2]
Ionisation
energy
0 1 2 3 4 5 6 7 8 9 10 11 12 13
Ionisation number
Sharp rise between 3rd and 4th (1)
Sharp rise between 11th and 12th (1)
For 2,8,3 (pattern the wrong way round) = 1
iii)
Sketch and label the shapes of the orbitals present in an aluminium atom. [2]
s spherically drawn (1) p figure of 8 shape drawn (1)