Zadanie 5e
Wzorowane na: Chemistry HL Paper 2, November 2023, TZ2, pytanie 5(e). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Informacja do zadań 5a-5h.
Aluminium is a low-density metal that is used in lightweight alloys.
Polecenie
Like aluminium chloride, iron(III) chloride forms dimers in the vapour phase. Iron, however, is a transition element and aluminium is not.
(i) Outline, in terms of its electronic structure, what identifies a transition element.
(ii) The graph shows the first four ionization energies of aluminium and of iron. Variable oxidation state is a common property of transition elements. Discuss, using the graph, why iron has variable oxidation states but aluminium does not.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
(i) it has a partially filled d sub-level «in the atom or in at least one common ion» ✔
(ii) the successive ionization energies of iron rise steadily AND those of aluminium jump abruptly between the third and fourth electron ✔
aluminium loses only three electrons / forms only Al3+ / has only the +3 oxidation state ✔
the further ionization energies of iron are close in value to the earlier ones, so iron can lose different numbers of electrons «depending on the oxidizing agent present» ✔
Schemat punktowania
(i) [1]. (ii) [3]: M1 for the contrast between the two curves, M2 for the single oxidation state of aluminium, M3 for the reason why iron can lose a variable number of electrons.