Date | November 2018 | Marks available | 2 | Reference code | 18N.2.hl.TZ0.4 |
Level | HL | Paper | 2 | Time zone | TZ0 |
Command term | Predict | 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.
Explain why the radius of the sodium ion, Na+, is smaller than the radius of the oxide ion, O2−.
Sketch a graph to show the relative values of the successive ionization energies of boron.
Predict, giving your reasons, whether Mn2+ or Fe2+ is likely to have a more exothermic enthalpy of hydration.
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”.
isoelectronic/same electronic configuration/«both» have 2.8 ✔
more protons in Na+ ✔
Sketch showing:
largest increase between third and fourth ionization energies ✔
IE1 < IE2 < IE3 < IE4 < IE5 ✔
Fe2+ AND smaller size/radius
OR
Fe2+ AND higher charge density ✔
stronger interaction with «polar» water molecules ✔
M1 not needed for M2.