IB Chemistry SL 3.1.3 Periodicity

Practise explaining recurring trends in atomic and ionic radius, first ionisation energy, electron affinity and electronegativity. Separate increasing nuclear charge from…

Exam points

explain an across-period trend through rising nuclear charge with similar shielding
explain a down-group trend through additional shells, distance and increased shielding
justify an ionisation-energy anomaly using subshell energy or paired-electron repulsion

[Maximum number: 3]

Chlorine undergoes many reactions.

(a)

State, giving a reason, whether the chlorine atom or the chloride ion has a larger radius.

[ 1 ]

$\mathrm{Cl}^{-}$ AND more «electron-electron» repulsion

Marking guidance:

Accept $\mathrm{Cl}^{-}$ AND has an extra electron.

(b)

Outline why the chlorine atom has a smaller atomic radius than the sulfur atom.

[ 2 ]

Cl has a greater nuclear charge/number of protons/ $\mathrm{Z}_{\text {eff }}$ «causing a stronger pull on the outer electrons»

same number of shells

OR

same «outer» energy level

OR

similar shielding

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3.1.3—Periodicity question 1

Question (a)

Question (b)