Topic 2 - Exam-style questions

Question 1

Describe the motion of the atoms in a crystal of silicon dioxide

Answer 1

the atoms vibrate around in a fixed position

Question 2

in terms of structure and bonding, describe what happens to the atoms in a crystal of silicon dioxide when it melts

Answer 2

the covalent bonds are broken and the atoms are free to move

Question 3

state the type of intermolecular force(s) in BF3

Answer 3

London

Question 4

state the type of intermolecular force(s) in NF3

Answer 4

London, dipole-dipole

Question 5

what type of bond is formed between a molecule of BF3 and NF3

Answer 5

dative covalent bond

Question 6

by referring to the types of intermolecular force involved, explain why energy must be supplied in order to boil liquid hydrogen chloride

Answer 6

energy is needed to overcome the London and Dipole-Dipole forced

Question 7

Explain why the boiling point of hydrogen bromide lies between those of hydrogen chloride and hydrogen iodide

Answer 7

HBr has an intermediate size, as the London forces depend on molecular size

Question 8

Explain why the boiling point of hydrogen fluoride is higher than that of hydrogen chloride

Answer 8

There are hydrogen bonds in HF, so the intermolecular forces are stronger than HCl

Question 9

What is the electronic configuration of aluminium

Answer 9

1s2 2s2 2p6 3s2 3p1

Question 10

what is the electronic configuration of vanadium

Answer 10

1s2 2s2 2p6 3s2 3p6 4s2 3d3

Question 11

describe the bonding present in metals

Answer 11

the attraction between positively charged nuclei and the delocalised electrons in a cloud of electrons

Question 12

explain how the bonding and structure of metals allow it to be electrical conductors

Answer 12

the freely moving electrons can carry a charge

Question 13

explain how the bonding and structure of metals allow it to be malleable

Answer 13

the layers can slide over each other, whilst the attractive forces remain the same throughout the lattice

Question 14

suggest a reason why aluminium is a better conductor of electricity than magnesium

Answer 14

Aluminium has more outer shell electrons,
AL+3 and MG+2

Question 15

state and explain the trend in electronegativity of the elements across Period 3 from sodium to chlorine

Answer 15

there is an increase in electronegativity across a period, as the nuclear charge increases whilst shielding stays the same

Question 16

why does a molecule of CH3Cl have a permanent dipole but CCL4 is not polar

Answer 16

CH3Cl has asymmetry of polar C-Cl bonds

Question 17

use the kinetic theory to describe the changes that take place as calcium oxide is heated from 25°C to a temperature above its melting point

Answer 17

as temperature increases until the vibrations are so violent that the ions break free at the melting point

Question 18

state 2 properties of calcium oxide that depends on its bonding

Answer 18

• has a high melting and boiling point
• is an electrical conductor as a liquid or gas

Question 19

Which of the following has the highest melting temperature:
- Hg
- K
-C10H22
- SiO2

Answer 19

SiO2

Question 20

Which of these has a dative covalent bond:
- NH3
- OH-
- H2O
- H3O+

Answer 20

H3O+

Question 21

The bonding in lithium iodide has some covalent character because:
- the lithium ion polarizes the iodine ion
- the iodide ion polarizes the lithium ion
- there is a large difference in electronegativity between lithium and iodide
- there is a small difference in electronegativity between lithium and iodide

Answer 21

the lithium ion polarizes the iodine ion

Question 22

which of the following is a pure form of carbon that has both hexagonal and pentagonal rings in its structure and can conduct electricity:
- charcoal
- buckminsterfullerene
- diamond
- graphite

Answer 22

buckminsterfullerene

Question 23

In which series of compounds does the covalent character increase, going from left tor right:
- NaCl, MgCl2, AlCl3, SiCl4
- SiO2, Al2O3, MgO, Na2O
- LiI, NaI, KI, RbI
- KI, KBr, KCl, KF

Answer 23

NaCl, MgCl2, AlCl3, SiCl4

Question 24

Samples of 1-chloropropane and 1 bromopropane are warmed with water containing dissolved silver nitrate in the presence of ethanol. The 1-chloropropane reacts more slowly because:
- the C-Cl bond is more polar than C-Br bond
- the C-Br bond is more polar than C-Cl bond
- 1-chloropropane is less soluble than 1-bromopropane
- 1-chloropropane is a weaker oxidizing agent than 1-bromopropane

Answer 24

the C-Cl bond is more polar than C-Br bond

Question 25

What is the total number of electrons in the covalent bonds in a beryllium chloride molecule, BeCl2? - 2 - 4 - 6 - 8

Answer 25

4

Question 26

Which of the following molecules does not absorb infrared radiation? - N2 - NO2 - CO - CO2

Answer 26

N2

Question 27

The bonding in gaseous hydrogen halides is best described as: - mainly covalent with an increasing tendency towards ionic as you go down the group. - mainly covalent with an increasing tendency towards ionic as you go up the group. - mainly ionic with an increasing tendency towards covalent as you go down the group. - mainly ionic with an increasing tendency towards covalent as you go up the group.

Answer 27

mainly ionic with an increasing tendency towards covalent as you go down the group.

Question 28

White phosphorus consists of: - a giant structure of atoms - a giant structure of ions - small molecules - single atoms

Answer 28

small molecules

Question 29

Show, and clearly label , the alpha and pi bonds between 2 carbon atoms

Answer 29

see notes

Question 30

explain why alpha bonds and stronger than pi bonds

Answer 30

alpha bonds have a strong overlap between the s-orbitals, so there's a higher electron density. However, the pi bond has weak overlap between the p-orbitals, as they are parallel to each other

Question 31

Describe the result of the test for the presence of a carbon double bond in E-but-2-ene, using bromine water. Give the displayed formula of the organic product.

Answer 31

orange to colourless Br - C(CH3, H) - C (CH3, H) - OH

Question 32

Another test for carbon double bonds is the reaction with acidified potassium manganate(VII). Describe the result of this test using but-1-ene and give the displayed formula of the organic product.

Answer 32

pink to colourless H - C (OH, H) - C (OH, H) - CH2 - CH3

Question 33

‘Polybutene’ is the name used by cosmetic companies for a mixture of poly(but-1-ene) and poly(but-2-ene). An American “eco-cosmetics” company says that though ‘polybutene’ is considered a safe ingredient in lip gloss, it is non-sustainable to use it. Suggest one reason to justify this statement.

Answer 33

polybutene is made from non-renewable resources

Question 34

Explain why the boiling temperature of CH3F is greater than that of F2, referring to the intermolecular forces present.

Answer 34

CH3F has permanent dipole-dipole forces present, so more energy is needed to overcome these forces

Question 35

Sodium and sodium chloride can both be good conductors of electricity. Under what conditions do these substances conduct electricity? Compare the method of conductivity in each case.

Answer 35

Sodium conducts as a solid, whilst sodium chloride can only conduct molten. This is because sodium has delocalised electrons to carry the charge, whilst sodium chloride has ions to carry the charge.

Question 36

Describe the structure of a metal.

Answer 36

closely-packed lattice with cations

Question 37

Describe the bonding in a metal.

Answer 37

the attraction between cations and the delocalised electrons

Question 38

Explain why the melting temperature of magnesium (650 °C) is much higher than that of sodium (98 °C).

Answer 38

Magnesium has a larger charge, more electrons, and the magnesium ion is smaller than the sodium ion. So, there's a greater attraction for the delocalised sea of electrons

Question 39

Explain how metals conduct electricity

Answer 39

they have delocalised electrons which are free to move and can carry a charge