Topic 4 Bonding
4.1
Ionic Bonding and Covalent Bonding (Lewis Structures)
1. Which substance exhibits only ionic bonding?
2. Which compound contains ionic bonds?
A.
NaNO3
A.
Magnesium bromide, MgBr2
B.
H2SO4
B.
Dichloromethane, CH2C12
C.
NH4C1
C.
Ethanoic acid, CH3COOH
D.
MgBr2
D.
Silicon tetrachloride, SiCl4
4. Which compound has the greatest ionic character?
3.Which compound is most ionic?
A.
HC1
B.
KF
C.
MgCl2
D.
Al 2O3
HL/SL
A.
MgS
B.
HCl
C.
CO2
D.
CaO
5. The compound formed between magnesium and oxygen is primarily
A.
ionic with a formula of MgO.
B.
ionic with a formula of MgO2.
C.
covalent with a formula of MgO.
D.
covalent with a formula of MgO2.
6. When the substances below are arranged in order of increasing carbon-carbon bond length (shortest bond
first), what is the correct order?
I.
H2CCH2
II. H3CCH3
III.
A. I<II<III
B.
I<III<II
C.
II<I<III
D.
III<II<I
7. Draw the Lewis structure of carbon dioxide.
[1 mark]
8. Draw a Lewis structure for fluorine.
Name and describe the bonding within the molecules in liquid fluorine.
Write the electronic structures of both sodium and fluorine and describe how the atoms
combine to form sodium fluoride.
9.
(i)
[3]
[4]
Draw the Lewis structures for carbon monoxide, carbon dioxide and the carbonate ion
[3]
(ii) Identify the species with the longest carbon-oxygen bond and explain your answer.
[3]
(iii) Draw the Lewis structure of ClF3
[1]
Topic 4 Bonding
4.2
Covalent Bonding (Shape, bond angles and VSEPR)
1. Which molecule has the largest bond angle?
HL/SL
2.Which molecule or ion does not have a tetrahedral shape?
A.
BF3
A
XeF4
B.
CF4
B
SiC14
C.
NF3
C
BF4-
D.
OF2
D.
NH4+
3. How do the bond angles between the hydrogen atoms and the central atom in H2O, NH3 and CH4
compare?
A.
The bond angles in these three molecules are all equal.
B.
The bond angles in CH4 are less than those in NH3 which are less than those in H2O.
C.
The bond angles in NH3 are less than those in CH4 which are less than those in H2O.
D.
The bond angles in H2O are less than those in NH3 which are less than those in CH4.
4. When the species NH2-,NH3 and NH4+ are arranged in increasing order of H-N-H bond angle, the correct order is
A.
NH2-,,NH3, NH4+
+
B.
NH4 ,NH3, NH2 ,
c.
NH3, NH4+, NH2-
D-
NH3, NH2-, NH4+
6. Which molecule is linear?
A.
SO2
B.
CO2
C.
H2S
D.
Cl 2O
5.
Which has the smallest bond angle?
-
A.
NH3
B.
CO2
C.
H2O
D.
CH4.
7. Draw electron dot structures for methane, ammonia and water. Use these structures to explain why the
molecular bond angles decrease in the order;
methane > ammonia > water
[7]
8. Sketch and name the shape of each of the following molecules:
(i)
SiH4
[2]
(ii)
PH3
[2]
State the bond angle in SiH4 and explain why the bond angle in PH3 is less than in SiH4.
9. (i)
Draw Lewis structures to represent BF3, NF3 and BF4- .
[2]
[3]
(ii) Use the principles of the Valence Shell Electron Pair Repulsion (VSEPR) theory to
predict the shapes of the above three species. Compare and account for the bond angles
in NF3 and BF4- in terms of VSEPR theory.
[5]
10. (a) Draw the Lewis structure of methanoic acid, HCOOH.
(b)
In methanoic acid, predict the bond angle around the
(i)
carbon atom...........................................................................................................................
(ii) oxygen atom bonded to the hydrogen atom. ..........................................................................
(c)
11a.
b.
State and explain the relationship between the length and strength of the bonds between the
carbon atom and the two oxygen atoms in methanoic acid
[1]
[2]
[3]
State the H—N—H bond angle in an ammonia molecule.
[1]
Explain why the ammonia molecule is polar.
[1]
Ammonia reacts with hydrogen ions forming ammonium ions, NH4+.
(i)
State the H—N—H bond angle in an ammonium ion.
(ii)
Explain why the H—N—H bond angle of NH3 is different from the H—N—H bond
angle of NH4+; referring to both species in your answer.
[1]
[3]
4.3
Topic 4 Bonding
HL/SL
Covalent Bonding (Bond Polarity)
1.Which molecule has the greatest polarity?
A.
Fluorine
B.
Hydrogen fluoride
C.
Hydrogen chloride
D.
Tetrafluoromethane
2. Which substance is the most polar?
A.
CH4
B.
CF4
C.
CH2F2
D.
CH2C12
3. Which molecule has polar bonds but is nonpolar?
A.
N2
B.
O3,
C.
CO2,
D.
NH,
4. Which molecule is non-polar?
A.
ClF
B.
PF3
C.
CF4
D.
CFCl 3
5. Explain the term polar bond. Predict and explain the polarity of the bonds within BF3
and NF3. State whether BF3 and NF3 are polar molecules. Explain your answer.
6.
[5]
Compare the polarity of the bonds N-Cl and C-Cl. Are the molecules NCl3 and CCl 4 polar
or non-polar? In all your answers give your reasons.
[5]
2.
3.
Topic 4 Bonding
4.4
Metallic Bonding
HL/SL
1.
Which is the best description of metallic bonding?
A.
The attraction between oppositely charged ions
B.
The attraction between protons and electrons
C.
The attraction between positive ions and delocalised electrons
D.
The attraction between nuclei and electron pairs
Describe the type of bonding in sodium metal and explain why sodium is a good
conductor of electricity.
[4]
Explain why the melting point of the elements increase in the order;
sodium < magnesium < aluminium < silicon
[5]
Topic 4 Bonding
Covalent Bonding (Shape, bond angles and VSEPR)
4.5
HL ONLY
1.The geometry and bond angle of the sulfite ion (SO 32-) are best described as
A.
pyramidal, 107º.
B.
tetrahedral, 109°.
C.
bent, 104°.
D.
trigonal planar, 120°
2. The shape of the triiodide ion, I3, is best described as
A.
bent.
B.
linear.
C.
T-shaped.
D.
triangular.
3.
When the Lewis structure for HCOOCH3 is drawn, how many bond pairs and how many lone pairs of ;
electrons are present?
Bond pairs
Lone pairs
A.
8
4
B.
7
5
C.
7
4
D.
5
5
4. The carbon-carbon-carbon bond angle in CH3CHCH2 is closest to
A.
180°.
B.
120°.
C.
109°.
D.
90°.
g Which of the following species is (are) planar (has (have) all the atoms in one plane)?
i.
CO32-
ii,
NO3-
iii.
SQ32-
A.
I only
B.
II only
C.
I and II only
D.
II and III only
6.
Draw Lewis (electron dot) structures for the following ions.
N02-
NO2+
Determine and explain the shape of each ion.
[6]
7. /Draw and name the shape of each of the following:
(i)
(ii)
XeF4
[2]
NH4+
[2]
(iii) PCI6-
8 (a)
[2]
Draw Lewis structures of the following species.
BF4-
(b)
H2CO
NO2+
NO2-
Predict the shape and bond angle of each of the species in (a), explaining your choice using
VSEPR theory.
[4]
[8]
Topic 4 Bonding
4.6
Intermolecular Forces and Physical Properties
HL/SL
I. In which of the following substances would hydrogen bonding be expected to occur?
I.
CH4
II
CH3C00H
III
CH3OCH3
2, Which compound is the most soluble in water?
A.
II only
A
Methane
B.
I and III only
B
Propane
C.
II and III only
C
Propan-1-ol
D.
I, II, and III
D.
Pentan-1-ol
2 As the size of the halogen molecules, X2, increases down the group, their boiling points
A.
decrease due to decreasing electronegativity.
B.
decrease due to decreasing bond energies.
C.
increase due to increasing permanent dipole-dipole attraction.
D.
increase due to increasing van der Waals' forces.
4 Which of the compounds H20, H2S, H2Se and H2Te has the highest boiling point?
A.
H20
B.
H2S
C.
H2Se
D.
H2Te
5. Which intermolecular forces exist in dry ice, C02(s) ?
A.
Covalent bonds
B.
Dipole-dipole attractions
C
D.
Van der Waal's forces
Hydrogen bonds
b, (a) The boiling points of the hydrides of group 6 elements increase in the order
H2S<H2Se<H2Te<H20.
Explain the trend in the boiling points in terms of bonding.
[3]
(b) Identify which of the compounds butane, chloroethane, propanone and propan-1-ol are
(i) insoluble in water and give your reasoning.
[2]
(ii) water soluble and give your reasoning.
[2]
The types of bonding and structure in elements and compounds can be used to explain a
variety of physical properties. Use your knowledge of bonding and structure to answer each
of the following:
(i)
Explain why carbon (diamond) is a very hard substance and does not conduct electricity
but carbon (graphite) is very soft and is a good conductor.
[6]
(ii) Describe the bonding within and between the molecules in liquid fluorine.
[2]
(iii) Explain why lithium fluoride does not conduct electricity until it is heated above its
melting point.
[2]
8. Explain at the molecular level why ethanol (C2H5OH) is soluble in water, but cholesterol /
(C27H45OH) and ethane (C2H6) are not
[4]
Topic 4 Bonding
4.7
Hybridisation and Delocalisation
I
HL ONLY
What states of hybridisation are shown by the carbon atoms marked 1, 2, 3 in the structure below?
H2C = CH- -CH2-CsN
2
i
^ 3
A. sp2
sp2
sp
B. sp2
sp3
sp
c.
sp3
sp2
2
sp3
sp3
D. sp
sp
■
'•i
2 Which species contains no delocalised electrons?
A.
03
B.
NO;
3 The delocalisation of electrons is most likely to be significant in
A.
C.
C032B.
D.
CO,.
S02.
H2S04
2
C.
D.
HCOOH.
Ti02.
■^ Which statements about the following molecule are correct?
(CH3)2 CHCH=€HG<:CH=€H2
I.
Three carbon atoms are sp3 hybridized.
II.
Three carbon atoms are sp2 hybridized.
HI.
Two carbon atoms are sp hybridized.
5
Which
^^ is/are ^ hybridised?
I.
C2H4
H.
C2H6
C 3 H6
m.
A.
I and II only
B.
I,IIandin
A.
I only
C.
H and IH only
B.
I and H only
D.
I and IH only
C.
I and m only
D.
n and m only
-26. What type(s) of hybridation is/are used by carbon in the following compound?
H
H.
A.
sp2 only
B.
sp and sp2
C.
sp and sp3
D.
sp2 and sp3
■3. In which species can
8.
A.
CH3CH20
B.
CH3CO~
C.
03
D.
NO;
/C^
/C=N
the bonding not be described in terms of the delocalisation of % electrons?
What is the molecular shape and the hybridization of the nitrogen atom in NH3 ?
Molecular shape
Hybridization
A.
tetrahedral
sp
B.
trigonal planar
C.
trigonal pyramidal
sp2
D.
trigonal pyramidal
sp3
2
™,
sp
-3**{. I Explain the meaning of the term hybridisation. State the type of hybridisation shown \
by the central atoms in BF, and NF3.
}&• State the type of hybridisation in C2H2 and C2C14.
I {, The structure of the ethanoate ion can be written as shown below.
//
o~
/
-*- -► CH3 ----- C.
CH3 ------ C
o~
>o
The stability of the ethanoate ion suggests a different type of carbon to oxygen bond, (i)
Describe the actual carbon to oxygen bond in the ethanoate ion.
(ii)
Predict a value for the bond length of the carbon to oxygen bond in the ethanoate ion.
-4-
|2. Nitrogen forms a number of different compounds with hydrogen including
NH3
, ' ■ , - .
H2NNH2
HNN(H
(i)
Write Lewis electron dot structures for N2, NH3, H2NNH2 and HNNH.
(ii)
Compare the bond angles between the hydrogen atoms in H2NNH2 and HNNH.
Explain your reasoning.
(iii) Give the hybridisation of the nitrogen in N2, NH3 and HNNH.
13, Hydrazoic acid, N3H, can be represented by two possible Lewis structures in which the atoms
can be arranged as NNNH.
(i)
Draw the two possible Lewis structures of N3H.
(ii)
Predict the N—N—N and H—N—N bond angles in each case and give your
reasoning.
(iii) Predict the hybridization of the N atom bonded to the hydrogen atom in each case.
Topic 4 Bonding
Extension
4.8
HL ONLY
The electronegativity value of carbon is 2.5 and that of oxygen is 3.5.
|
Draw a Lewis (electron dot) structure for the carbon dioxide molecule, state its shape
and give the bond angle.
[3]
Using the concepts of molecular shape and bond polarity, predict, with an explanation,
whether or not the carbon dioxide molecule is polar.
Specify the hybridisation of the carbon atom in carbon dioxide.
Using ethane as your example, explain the terms hybridisation and sigma bonding, and
state the type of hybridisation shown by the carbon atoms in ethane.
[3]
[1 mark]
[5]
-2-
O Ethanoic acid contains two different types of carbon to oxygen bond. Explain how the
c>
* carbon and oxygen atoms combine to form each of those bonds and compare their bond
lengths and strengths.
4.
[7j
Carbon dioxide, the ethanoate ion, CH3COO , and the ethoxide ion,
C2H50~, all contain at least one bond between carbon and oxygen. In
which structure will the carbon to oxygen bond length be in between
those found in the other two structures? Explain your answer.
[3 marks]
-3N99/420/H(2)
5 (a)
(i)
(ii)
(b)
(c)
Butane, C4H10, propanal, C3H60, and propan-l-ol, C3H80 have very similar molar
masses (59 ± 1). Draw the Lewis structure of each of these molecules.
[3]
For each of the three molecules state how many carbon atoms are sp, sp2 and sp3
hybridised.
[3]
What are the values for:
(i)
HOC bond angle in propan-l-ol?
(ii)
HCO bond angle in propanal?
///
[1]
Explain:
(i)
why butane has the lowest boiling point of the three compounds.
[2]
(ii) why propan-1 -ol has the highest boiling point of the three compounds.
[2]
(iii) what type of intermolecular bonding occurs in propanal.
[2]