[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

[Maximum number: 1]

In which species does the underlined atom have an incomplete outer shell?

A

$\mathrm{BF}_{3}$

B

$\underline{\mathrm{CH}}_{3}^{-}$

C

$\mathrm{F}_{2} \underline{\mathrm{O}}$

D

$\mathrm{H}_{3} \underline{\mathrm{O}}^{+}$

[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 ]

[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 Pauling electronegativity values of elements can be used to predict the chemical properties of compounds.

Use the information in Table 1.1 to answer the following questions.

Table 1.1

(a)

(i)

Suggest the shape of a molecule of $\mathrm{H}_{2} \mathrm{~S}$ .

[ 1 ]

[Maximum number: 2]

Gallium is an element in Group 13.
A sample of gallium is analysed using a mass spectrometer. The mass spectrum produced is shown.

(a)

When gallium is heated in excess chlorine, gallium trichloride, $\mathrm{GaCl}_{3}$ , is made.

Draw the shape of the gallium trichloride molecule and suggest the Cl-Ga-Cl bond angle.
shape of molecule
bond angle

[ 2 ]

[Maximum number: 1]

Group 2 metals form alkaline solutions in water.

(a)

Beryllium oxide reacts with hydrochloric acid to form molecules of $\mathrm{BeCl}_{2}$ .

Deduce the bond angle in $\mathrm{BeCl}_{2}$ .

[ 1 ]

[Maximum number: 4]

The elements sodium to chlorine, in the third period, all form oxides.

(a)

Draw a diagram to show the shape of the molecule of each of the oxides, $\mathrm{SO}_{3}$ and $\mathrm{Cl}_{2} \mathrm{O}$ .

Name each shape.
In $\mathrm{SO}_{3}$ each oxygen atom forms a double bond with the sulfur atom.
$\mathrm{SO}_{3}$

[ 4 ]

[Maximum number: 4]

The elements sodium to sulfur react with chlorine. The melting points of some of the chlorides formed are shown.

(a)

Predict the shapes of $\mathrm{AlCl}_{3}$ and $\mathrm{PCl}_{3}$ .

Draw diagrams to show the shapes, name the shapes and state the bond angles.
$\mathrm{AlCl}_{3}$
shape
angle

[ 4 ]

(a)

Phosphorus reacts with chlorine to form $\mathrm{PCl}_{5}$ .

State the shape of and two different bond angles in a molecule of $\mathrm{PCl}_{5}$ .
shape of $\mathrm{PCl}_{5}$
bond angles in $\mathrm{PCl}_{5}$

[ 2 ]