[Maximum number: 1]

Sulfides are compounds that contain sulfur but not oxygen.

(a)

Carbon disulfide, $\mathrm{CS}_{2}$ , is a volatile liquid at room temperature and pressure.

[ 1 ]

(i)

Suggest the bond angle in a molecule of $\mathrm{CS}_{2}$ .

[ 1 ]

(a)

(i)

Draw a three-dimensional diagram showing the shape of the chloride. Give the Cl-Si-Cl bond angle.

[ 2 ]

[Maximum number: 2]

Tellurium is an element in Group 16. The most common isotope of tellurium is ${ }^{130} \mathrm{Te}$ . Its electronic configuration is $[\mathrm{Kr}] 4 \mathrm{~d}^{10} 5 \mathrm{~s}^{2} 5 p^{4}$ .

(a)

Te reacts with $\mathrm{F}_{2}$ at $150^{\circ} \mathrm{C}$ to form $\mathrm{TeF}_{x}$ . Molecules of $\mathrm{TeF}_{x}$ are octahedral with bond angles of $90^{\circ}$ .

Explain why $\mathrm{TeF}_{x}$ is octahedral with bond angles of $90^{\circ}$ .

[ 2 ]

[Maximum number: 1]

The elements silicon, phosphorus and sulfur are in Period 3 of the Periodic Table.

(a)

Table 1.1 shows some properties of the elements Si to S .

The first ionisation energy of P is not shown.

Table 1.1

[ 1 ]

(i)

Predict the shape of the $\mathrm{SCl}_{2}$ molecule.

[ 1 ]

(a)

Sulfur reacts with fluorine to form $\mathrm{SF}_{6}$ . State the shape and bond angle of $\mathrm{SF}_{6}$ .
shape of $\mathrm{SF}_{6}$
bond angle of $\mathrm{SF}_{6}$

[ 2 ]

(a)

Group 2 carbonates decompose when heated to form the metal oxide and carbon dioxide.

[ 1 ]

(i)

Suggest a mechanism for the decomposition of the carbonate ion by adding two curly arrows in Fig. 1.1.

Fig. 1.1

[ 1 ]

(b)

Potassium disulfite, $\mathrm{K}_{2} \mathrm{~S}_{2} \mathrm{O}_{5}$ , is another food additive. The disulfite ion, $\mathrm{S}_{2} \mathrm{O}_{5}{ }^{2-}$ , has the displayed formula shown in Fig. 1.2.

Fig. 1.2

Deduce the geometry (shape) around the $\mathrm{S}(\alpha)$ atom in $\mathrm{S}_{2} \mathrm{O}_{5}{ }^{2-}$ .
geometry around $\mathrm{S}(\alpha)$

[Maximum number: 2]

Oxides are compounds which usually contain oxygen combined with one other element.
Oxides are classified as follows.
acidic alkaline amphoteric basic

(a)

Another sulfur compound which is present in the Earth's atmosphere is carbonyl sulfide, OCS. The sequence of atoms in the molecule is oxygen-carbon-sulfur and the molecule is not cyclic.

[ 2 ]

(i)

Suggest a value for the O-C-S bond angle.

[ 2 ]

[Maximum number: 7]

Valence Shell Electron Pair Repulsion theory (VSEPR) is a model of electron-pair repulsion (including lone pairs) that can be used to deduce the shapes of, and bond angles in, simple molecules.

(a)

Complete the table below by using simple hydrogen-containing compounds. One example has been included.

[ 3 ]

(b)

Tellurium, Te, proton number 52, is used in photovoltaic cells.

When fluorine gas is passed over tellurium at $150^{\circ} \mathrm{C}$ , the colourless gas $\mathrm{TeF}_{6}$ is formed.

[ 4 ]

(i)

What will be the shape of the $\mathrm{TeF}_{6}$ molecule?

[ 1 ]

(ii)

What is the F-Te-F bond angle in $\mathrm{TeF}_{6}$ ?

[ 3 ]

[Maximum number: 2]

The elements of the third period of the Periodic Table, sodium to sulfur, all form chlorides by direct combination.

(a)

Sulfur forms the compound $\mathrm{S}_{4} \mathrm{~N}_{4}$ with nitrogen. The structure of $\mathrm{S}_{4} \mathrm{~N}_{4}$ is shown below. Assume all bonds shown are single bonds.

[ 2 ]

(i)

Which bond angle, a or b, in the $\mathrm{S}_{4} \mathrm{~N}_{4}$ molecule will be smaller? Explain your answer.

[ 2 ]

[Maximum number: 1]

What are the shapes of the molecules of water and boron trifluoride?

$\mathrm{H}_{2} \mathrm{O}$

$\mathrm{BF}_{3}$

linear

pyramidal

linear

trigonal

non-linear

pyramidal

non-linear

trigonal

Question 1

Question 1(a)

Question 1(a)(iii)

Question 1

Question 1(a)

Question 1(a)(iii)

Question 1

Question 1(e)

Question 1

Question 1(b)

Question 1(b)(v)

Question 1

Question 1(e)

Question 1

Question 1(a)

Question 1(a)(i)

Question 1(d)

Question 1

Question 1(f)

Question 1(f)(ii)

Question 1

Question 1(a)

Question 1(b)

Question 1(b)(ii)

Question 1(b)(iii)

Question 1

Question 1(c)

Question 1(c)(ii)

Question 1