Zadanie 2c, Paper 2, maj 2025, TZ2, Chemia IB HL

(i) the convergence limit «of the lines at the high-frequency end of the spectrum» ✔

(ii) energy per atom «$= \dfrac{579 \times 10^3\ \mathrm{J\,mol^{-1}}}{6.02 \times 10^{23}\ \mathrm{mol^{-1}}}$» = 9.62 × 10⁻¹⁹ «J» ✔

frequency «$= \dfrac{E}{h} = \dfrac{9.62 \times 10^{-19}}{6.63 \times 10^{-34}}$» = 1.45 × 10¹⁵ «s⁻¹» ✔

wavelength «$= \dfrac{c}{f} = \dfrac{3.00 \times 10^8}{1.45 \times 10^{15}}$» = 2.07 × 10⁻⁷ «m» / 207 «nm» ✔

(iii) germanium has the greater nuclear charge «32 protons compared with 31» ✔

the shielding is the same in both atoms, because the valence electrons are in the same energy level / the number of inner electrons is the same, so the valence electron of gallium is held less strongly ✔

(i) [1] convergence limit; accept 'high-energy limit of the continuum'. (ii) [3] M1 energy per atom; M2 frequency; M3 wavelength; award [3] for a correct final answer; ECF at each step. (iii) [2] M1 nuclear charge comparison; M2 shielding unchanged. Do not accept 'germanium atoms are smaller' for M1.