Chemistry 5070 · O Level · Simple molecules and covalent bonds

Simple molecules and covalent bonds — practice question

The sulfur isotopes are $^{32}_{16}\text{S}$ and $^{33}_{16}\text{S}$.
(a)[1]

How is the term isotopes defined?

(b)[3]

For $^{33}_{16}\text{S}$, fill in the numbers of neutrons, protons and the electronic configuration.

(c)[1]

Sulfur exists as simple molecules with a relative molecular mass of 256. What is the formula of a sulfur molecule?

(d(i))[1]

Sulfur has a low melting point and is a non-conductor of electricity. Explain why sulfur has a low melting point.

(d(ii))[1]

Why does sulfur not conduct electricity?

(e)[2]

Potassium sulfide is formed when sulfur reacts with potassium. Give the formula and the electronic configuration of the positive ion and the negative ion in potassium sulfide.

(f)[2]

Sulfur reacts with hydrogen to produce hydrogen sulfide, $\text{H}_2\text{S}$. Draw the dot-and-cross diagram to show the bonding in one molecule of hydrogen sulfide. Draw only the outer shell electrons.

(g)[1]

Hydrogen sulfide reacts with sulfur dioxide to give sulfur and water. Write the equation for this reaction.

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Atoms that have the same number of protons but a different number of neutrons” …

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