Practise ion formation, ionic formulae, dot-and-cross diagrams, lattice properties and conductivity using charges, tables and particle models.
This is a question about metals and their compounds.
In the absence of air, magnesium reacts with sulfur to form the ionic compound magnesium sulfide, MgS
Describe, in terms of electrons, the formation of the ions in magnesium sulfide.
Give the charges on the ions.
M1 magnesium (atom) loses two electrons
M2 sulfur (atom) gains two electrons (from magnesium)
M3 charge on magnesium (ion) 2+/Mg2+ AND charge on sulfur/sulfide (ion) 2−/S2−
two electrons
transferred from
magnesium (atom) to
sulfur (atom) scores M1
and M2
Explain why magnesium sulfide has a very high melting point.
M1 strong (electrostatic) force of attraction
M2 between magnesium ions /Mg2+ and sulfide ions /S2− ions
M3 large amount/lot of (heat/thermal) energy needed to overcome forces/attraction
ALLOW strong ionic bonds but No M1 or M2 if between atoms/molecules or any reference to intermolecular forces / covalent bonds
ACCEPT between oppositely charged ions
ACCEPT between positive and negative ions
ACCEPT large amount/lot of (heat/thermal) energy needed to break the bonds
IGNORE more energy
No M3 if reference to overcoming / breaking intermolecular forces / covalent bonds
This question is about Group 7, the halogens.
What is the charge on a bromide ion?
1-
1+
2-
2+
A
Sodium hydroxide dissolves in water, forming a strongly alkaline solution.
Ammonia dissolves in water, forming a slightly less alkaline solution.
Ammonium sulfate is used by gardeners as a fertiliser because it contains nitrogen.
Explain why the chemical formula of ammonium sulfate is (NH4)2SO4 Refer to the charges on the ions in your answer.
M1 ammonium ion is charged 1+/NH4+
AND sulfate ion is charged 2−/SO42−
M2 so charges balance/cancel (each other) OWTTE
ALLOW so that ammonium sulfate has no overall charge
M2 not dep on M1