CAIE A-Level Chemistry 3 Chemical Bonding

Practise explaining ionic, covalent, coordinate and metallic bonding and relating structure to shape and properties.

Covered syllabus points

3.1 Electronegativity and bonding 3.2 Ionic bonding 3.3 Metallic bonding 3.4 Covalent bonding and coordinate (dative covalent) bonding 3.5 Shapes of molecules 3.6 Intermolecular forces and bond properties 3.7 Dot-and-cross diagrams

[Maximum number: 8]

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)

Define electronegativity.

[ 1 ]

(b)

O and S are in Group 16 .

Explain the difference in the Pauling electronegativity values of O and S .

[ 2 ]

(c)

LiH is an ionic compound.

Draw a dot-and-cross diagram of LiH.
Include all electrons.

[ 2 ]

(d)

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

[ 1 ]

(e)

Complete Table 1.2 by placing a tick $(\checkmark)$ to show which of the compounds have molecules with an overall dipole moment.

Table 1.2

[ 2 ]

Correct completed table:

compound	$\mathrm{O}=\mathrm{C}=\mathrm{O}$	$\mathrm{O}=\mathrm{S}=\mathrm{O}$	$\mathrm{S}=\mathrm{C}=\mathrm{S}$	$\mathrm{S}=\mathrm{C}=\mathrm{O}$
overall dipole moment	no	yes	no	yes

[Maximum number: 2]

The Group 2 elements show metallic bonding.
Define metallic bonding.

[Maximum number: 6]

The strength of interaction between particles determines whether the substance is a solid, liquid or gas at room temperature.

(a)

Carbon monoxide, CO, is a gas at room temperature and pressure. It contains a coordinate bond.

[ 3 ]

(i)

Explain what is meant by coordinate bond.

[ 1 ]

(ii)

Draw a 'dot-and-cross' diagram to show the arrangement of outer electrons in CO . Show the electrons belonging to the C atom as x .

Show the electrons belonging to the O atom as •.

[ 2 ]

3 bonding pairs between C and O, $4 \cdot$ 's AND 2x's

1 lone pair on C, x x, AND 1 lone pair on $\mathrm{O}, \boldsymbol{\cdots}$ .

Figure for Answer to Question (ii) — CAIE A-Level Chemistry AS

(b)

Nitrogen, $\mathrm{N}_{2}$ , is also a gas at room temperature and pressure. Neither CO nor $\mathrm{N}_{2}$ is an ideal gas.

[ 3 ]

(i)

Complete the table by naming all the types of intermolecular forces (van der Waals') in separate samples of $\mathrm{N}_{2}(\mathrm{~g})$ and CO(g).

Table for Question (i) — CAIE A-Level Chemistry AS

[ 2 ]

$\mathrm{N}_{2}(\mathrm{~g})$ & CO(g)

instantaneous dipole-induced dipole &
instantaneous dipole-induced dipole

(and)

permanent dipole-permanent dipole

\end{tabular}

(ii)

Suggest why the bond in a molecule of CO contains a dipole moment.

[ 1 ]

[Maximum number: 5]

Sulfides are compounds that contain sulfur but not oxygen.

(a)

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

[ 5 ]

(i)

Draw a 'dot-and-cross' diagram of the $\mathrm{CS}_{2}$ molecule.

[ 2 ]

(ii)

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

[ 1 ]

$180^{\circ}$

(iii)

$\mathrm{CS}_{2}$ is a liquid under room conditions, while $\mathrm{CO}_{2}$ is a gas.

Explain what causes the difference in the physical properties between $\mathrm{CS}_{2}$ and $\mathrm{CO}_{2}$ .

[ 2 ]

M1 $\mathrm{CS}_{2}$ has more electrons

M2 So stronger induced dipole (forces) (between molecules)

All question bank results loaded

Covered syllabus points

3. Chemical bonding question 1

Question (a)

Question (b)

Question (c)

Question (d)

Question (e)

3. Chemical bonding question 2

3. Chemical bonding question 3

Question (a)

Question (i)

Question (ii)

Question (b)

Question (i)

Question (ii)

3. Chemical bonding question 4

Question (a)

Question (i)

Question (ii)

Question (iii)