Zadanie 3a
Wzorowane na: Chemistry SL Paper 2, May 2026, TZ2, pytanie 3(a). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Informacja do zadań 3a-3c.
Magnesium and sodium are reactive metals with many practical uses.
Polecenie
(i) Describe the structure of solid magnesium and state the forces that hold it together.
(ii) Explain why a piece of magnesium can be hammered into a new shape without breaking.
(iii) Explain why the melting point of magnesium is higher than that of sodium.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz CKE i punktacja
Odpowiedź z klucza
(i) Structure: «lattice of» Mg / positive ions / cations AND sea of / delocalized «valence» electrons ✔
Forces: electrostatic attraction «between the cations and the delocalized electrons» ✔
(ii) «layers of» cations slide over each other without breaking the bonding ✔
OR changing the positions of the atoms does not disrupt the bonding / forces of attraction
OR metallic bonds are non-directional
(iii) Mg has the higher charge density «Mg2+ has a higher charge and a smaller radius than Na+; two delocalized electrons per atom instead of one» ✔
stronger metallic bonding / electrostatic forces «in Mg, so more energy is needed to separate the particles» ✔
Schemat punktowania
(i) [2] M1 lattice of cations AND delocalized electrons; M2 electrostatic attraction; do not accept ‘positive nucleus’ for cations. (ii) [1]. (iii) [2] M1 higher charge density of Mg; M2 stronger metallic bonding; do not accept ‘stronger intermolecular forces’.