S ct on A M lt l
Qn
1
Cho c Q
2
3
st ons
4
5
6
7
8
9
10
Ans
1.
How do bond length and bond strength vary as the number of bonds between two atoms
increases?
A.
2.
3.
Bond L ngth
Increase
Bond str ngth
Increase
B.
Increase
Decrease
C.
Decrease
Increase
D.
Decrease
Decrease
Which substance will NOT conduct an electric current?
A.
C(s) [graphite]
B.
NaF (l)
C.
CaO (s)
D.
KI (aq)
Which is the best description of ionic bonding?
A.
The electrostatic attraction between oppositely charged ions
B.
The electrostatic attraction between positive ions and delocalised electrons
C.
The electrostatic attraction between positive ions and delocalised negative ions
D.
The electrostatic attraction between positively charged nuclei and an electron pair
Page 2 of
4.
5.
6.
7.
8.
Which molecule contains a dative covalent (coordinate) bond?
A.
HCN
B.
H2O2
C.
CO2
D.
NH4+
Which molecule has the greatest polarity?
A.
Fluorine
B.
Hydrogen fluoride
C.
Hydrogen chloride
D.
Tetrafluoromethane
Which molecule has the shortest carbon – oxygen bond length?
A.
CO
B.
CO2
C.
CH3CH2OH
D.
CH3COOH
Which of the following formulae is least likely to represent a natural compound?
A.
C2H2
B.
NCl5
C.
N2H4
D.
SF6
Which substance is made up of a lattice of positive ions and free moving electrons?
A.
Sodium
B.
Sulfur
C.
Graphite
D.
Sodium chloride
Page 3 of
9.
Metallic bonding depends to a large extent on delocalised electrons. Which of the following
metallic properties is NOT a consequence of metallic bonding?
A.
Ductility
B.
Magnetism
C.
Electrical conductivity
D.
High boiling point
10. The Voyager 2 probe has shown that the surface of Triton, a moon of the planet
Neptune, contains condensed methane which flows rapidly.
Which statement explains the flow within the condensed methane?
A.
Condensed methane has a metallic structure.
B.
Methane molecules contain strong C-H bonds.
C.
Methane molecules have a tetrahedral structure.
D.
The intermolecular forces between methane molecules are weak.
Page 4 of
S ct on B Str ct r d Q
st ons 20 m rks
11
Boron trifluoride, BF3 and aluminium fluoride, AlF3 differ markedly in their physical
properties.
compound
melting point/oC
BF3
-144
AlF3
1291
a)
Deduce the type of bonding present in each of these compounds and draw dot-and-cross
diagrams to illustrate their bonding. Explain how the type of bonding present results in the
very different melting points.
[6]
BF3 í covalent bond because it has lower m.p than AlCl3. As BF3 has no polar,
the intermolecular force of attraction between atoms is id-id, which is weak and require
less energy to break the attraction. Therefore, mp is low. AlF3 has strong ionic bonding,
which is the electrostatic force of attraction between oppositely charged ion. Therefore,
more energy is needed and mp is high.
b)
Boron trifluoride forms a compound with ammonia.
(i)
Describe the type of bond that is formed during this reaction and write equation to
show the reaction.
[2]
BF3 +NH3 -> BF3NH3
This is a a dative covalently bond
(ii)
Draw dot-and-cross diagram to illustrate the bonding of the product.
Page 5 of
[1]
12.
The elements magnesium and nitrogen and the compound magnesium nitride can be used
to show the connection between bonding, structure and physical properties.
(a)
Describe the type and nature of bonding in magnesium metal and explain why magnesium
is a good conductor of electricity.
[2]
Magnesium metal has metallic bonding, wich is the electrostatic force of attraction
between postively cations and delocalised electrons. The delocalised electrons that
can flow help them to conduct electricity
(b)
Draw a Lewis structure for nitrogen. Name and describe the bonding within the nitrogen
molecules and between the molecules in liquid nitrogen.
[3]
There's a weak covalent bond within nitrogen molecules and really weak
id-id forces between molecules in liquid nitrogen
(c)
Predict and explain whether magnesium nitride is an ionic or covalent compound. Hence,
predict whether its melting point is high or low and whether it conducts electricity.
[3]
Magnesium nitride is an ionic compound because it's the electrostatic force of attraction
between oppositely charged ions (Mg2+ and N3-). The melting point is high because the
dipole in ionic bonding is strong and requires lots of energy to break it. It can conduct energy
in aq or l form only because at those states, ions are free to move
(d)
Write the electronic structures of both magnesium and nitrogen and describe how the
atoms combine to form magnesium nitride.
[1]
Mg: 1s2 2s2 2p6 3s2; N: 1s2 2s2 2p3
Nitrogen takes electron from Mg outer shell to form ionic compound
Page 6 of
13.
Sketch the variation in net dipole moment for the three substances: tetrachloromethane
(CCl4), chloromethane (CH3Cl) and fluoromethane (CH3F). Explain your answers in terms
of molecular geometry and bond polarity.
[2]
Net dipole
moment/ D
0
CCl4
CH3Cl
Page of
CH3F