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Date November 2018 Marks available 2 Reference code 18N.2.hl.TZ0.4
Level HL Paper 2 Time zone TZ0
Command term Sketch Question number 4 Adapted from N/A

Question

Properties of elements and their compounds can be related to the position of the elements in the periodic table.

Explain the decrease in atomic radius from Na to Cl.

[2]
a.

Explain why the radius of the sodium ion, Na+, is smaller than the radius of the oxide ion, O2−.

[2]
b.

Sketch a graph to show the relative values of the successive ionization energies of boron.

[2]
c.

Predict, giving your reasons, whether Mn2+ or Fe2+ is likely to have a more exothermic enthalpy of hydration.

[2]
d.

Markscheme

nuclear charge/number of protons/Zeff increases «causing a stronger pull on the outer electrons» ✔

same number of shells/«outer» energy level/shielding ✔

 

Accept “atomic number” for “number of protons”.

a.

isoelectronic/same electronic configuration/«both» have 2.8 ✔

more protons in Na+

b.

Sketch showing:

largest increase between third and fourth ionization energies ✔

IE1 < IE2 < IE3 < IE4 < IE5

c.

Fe2+ AND smaller size/radius

OR

Fe2+ AND higher charge density ✔

 

stronger interaction with «polar» water molecules ✔

 

M1 not needed for M2.

d.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.
[N/A]
d.

Syllabus sections

Additional higher level (AHL) » Topic 12: Atomic structure » 12.1 Electrons in atoms
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Additional higher level (AHL) » Topic 12: Atomic structure
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