Edexcel A Level Chemistry
Topic 2
Bonding
and Structure
Topic 2 explains how particles are held together and how bonding affects structure and physical properties. This topic covers ionic bonding, covalent bonding, molecular shapes, electronegativity, polarity, intermolecular forces, solvent choice, metallic bonding and the relationship between structure and behaviour.
Exam Papers
Paper 1 & 2
9CH0/01 and 9CH0/02
Specification Points
2.1 – 2.27
27 points covered
Topic Parts
7 parts
Revision notes available
Exam Board
Edexcel
Pearson 9CH0
Revision Notes
Work through each part of Edexcel Topic 2 in a structured sequence.
Ions and lattices
Ionic
Bonding
Bonding
1
Available
Ionic Bonding
Ion formation, dot-and-cross diagrams, ionic lattices, ionic radius, ionic charge, ion migration and physical properties.
Start revisingShared electrons
Covalent
Bonds
Bonds
2
Available
Covalent Bonding
Covalent attraction, dot-and-cross diagrams, bond length, bond strength and dative covalent bonding.
Start revisingElectron pairs
Molecular
Shapes
Shapes
bond angles and 3D arrangement
3
Available
Shapes of Molecules
Electron-pair repulsion theory, bond angles and predicting the shapes of molecules and ions.
Start revisingBond polarity
Polar
Molecules
Molecules
4
Available
Polar Molecules
Electronegativity, polar bonds, non-polar molecules and using molecular symmetry to predict overall polarity.
Start revising5
Available
Metallic Bonding
Giant metallic lattices, metal ions, delocalised electrons, electrical conductivity and melting temperature.
Start revisingBetween molecules
Intermolecular
Forces
Forces
6
Available
Intermolecular Forces
London forces, permanent dipole-dipole forces, hydrogen bonding and boiling temperature trends.
Start revisingStructure and properties
Structure
Types
Types
bonding, particles and properties
7
Available
Structure Types
Giant ionic, giant covalent, giant metallic and simple molecular structures linked to physical properties.
Start revisingSpecification Coverage
Topic 2 Bonding and Structure – Edexcel A Level Chemistry
The following specification points outline the knowledge and skills students are expected to demonstrate for Topic 2.
2A: Bonding
2.1
know that ionic bonding is the strong electrostatic attraction between oppositely charged ions
2.2
understand the effects that ionic radius and ionic charge have on the strength of ionic bonding
2.3
understand the formation of ions in terms of electron loss or gain
2.4
be able to draw electronic configuration diagrams of cations and anions using dot-and-cross diagrams
2.5
understand reasons for the trends in ionic radii down a group and for a set of isoelectronic ions, e.g. N3- to Al3+
2.6
understand that the physical properties of ionic compounds and the migration of ions provide evidence for the existence of ions
2.7
know that a covalent bond is the strong electrostatic attraction between two nuclei and the shared pair of electrons between them
2.8
be able to draw dot-and-cross diagrams to show electrons in covalent substances, including:
i
molecules with single, double and triple bonds
ii
species exhibiting dative covalent, coordinate, bonding, including Al2Cl6 and ammonium ion
2.9
understand the relationship between bond lengths and bond strengths for covalent bonds
2.10
understand that the shape of a simple molecule or ion is determined by the repulsion between the electron pairs that surround a central atom
2.11
understand reasons for the shapes of, and bond angles in, simple molecules and ions with up to six outer pairs of electrons, any combination of bonding pairs and lone pairs. Examples should include BeCl2, BCl3, CH4, NH3, NH4+, H2O, CO2, PCl5(g) and SF6(g) and related molecules and ions; as well as simple organic molecules in this specification.
2.12
be able to predict the shapes of, and bond angles in, simple molecules and ions analogous to those specified above using electron-pair repulsion theory
2.13
know that electronegativity is the ability of an atom to attract the bonding electrons in a covalent bond
2.14
know that ionic and covalent bonding are the extremes of a continuum of bonding type and that electronegativity differences lead to bond polarity in bonds and molecules
2.15
understand that molecules with polar bonds may not be polar molecules and be able to predict whether or not a given molecule is likely to be polar
2.16
understand the nature of intermolecular forces resulting from the following interactions:
i
London forces, instantaneous dipole-induced dipole
ii
permanent dipoles
iii
hydrogen bonds
2.17
understand the interactions in molecules, such as H2O, liquid NH3 and liquid HF, which give rise to hydrogen bonding
2.18
understand the following anomalous properties of water resulting from hydrogen bonding:
i
its relatively high melting temperature and boiling temperature
ii
the density of ice compared to that of water
2.19
be able to predict the presence of hydrogen bonding in molecules analogous to those mentioned above
2.20
understand, in terms of intermolecular forces, physical properties shown by materials, including:
i
the trends in boiling temperatures of alkanes with increasing chain length
ii
the effect of branching in the carbon chain on the boiling temperatures of alkanes
iii
the relatively low volatility, higher boiling temperatures, of alcohols compared to alkanes with a similar number of electrons
iv
the trends in boiling temperatures of the hydrogen halides, HF to HI
2.21
understand factors that influence the choice of solvents, including:
i
water, to dissolve some ionic compounds, in terms of the hydration of the ions
ii
water, to dissolve simple alcohols, in terms of hydrogen bonding
iii
water, as a poor solvent for compounds, to include polar molecules such as halogenoalkanes, in terms of inability to form hydrogen bonds
iv
non-aqueous solvents, for compounds that have similar intermolecular forces to those in the solvent
2.22
know that metallic bonding is the strong electrostatic attraction between metal ions and the delocalised electrons
Practical
Possible practicals: investigating the migration of ions, for example in a U-tube of copper(II) chromate, and seeing the effect of a charged rod on a flow of water.
2B: Structure
2.23
know that giant lattices are present in:
i
ionic solids, giant ionic lattices
ii
covalently bonded solids, such as diamond, graphite and silicon(IV) oxide, giant covalent lattices
iii
solid metals, giant metallic lattices
2.24
know that the structure of covalently bonded substances such as iodine, I2, and ice, H2O, is simple molecular
2.25
know the different structures formed by carbon atoms, including graphite, diamond and graphene
2.26
be able to predict the type of structure and bonding present in a substance from numerical data and/or other information
2.27
be able to predict the physical properties of a substance, including melting and boiling temperature, electrical conductivity and solubility in water, in terms of:
i
the types of particle present, atoms, molecules, ions, electrons
ii
the structure of the substance
iii
the type of bonding and the presence of intermolecular forces, where relevant
Specification Coverage
Topic 2 Bonding and Structure – Edexcel A Level Chemistry
The following specification points outline the knowledge and skills students are expected to demonstrate for Topic 2.
2A: Bonding
2.1
know that ionic bonding is the strong electrostatic attraction between oppositely charged ions
2.2
understand the effects that ionic radius and ionic charge have on the strength of ionic bonding
2.3
understand the formation of ions in terms of electron loss or gain
2.4
be able to draw electronic configuration diagrams of cations and anions using dot-and-cross diagrams
2.5
understand reasons for the trends in ionic radii down a group and for a set of isoelectronic ions, e.g. N3- to Al3+
2.6
understand that the physical properties of ionic compounds and the migration of ions provide evidence for the existence of ions
2.7
know that a covalent bond is the strong electrostatic attraction between two nuclei and the shared pair of electrons between them
2.8
be able to draw dot-and-cross diagrams to show electrons in covalent substances, including:
i
molecules with single, double and triple bonds
ii
species exhibiting dative covalent, coordinate, bonding, including Al2Cl6 and ammonium ion
2.9
understand the relationship between bond lengths and bond strengths for covalent bonds
2.10
understand that the shape of a simple molecule or ion is determined by the repulsion between the electron pairs that surround a central atom
2.11
understand reasons for the shapes of, and bond angles in, simple molecules and ions with up to six outer pairs of electrons, any combination of bonding pairs and lone pairs. Examples should include BeCl2, BCl3, CH4, NH3, NH4+, H2O, CO2, PCl5(g) and SF6(g) and related molecules and ions; as well as simple organic molecules in this specification.
2.12
be able to predict the shapes of, and bond angles in, simple molecules and ions analogous to those specified above using electron-pair repulsion theory
2.13
know that electronegativity is the ability of an atom to attract the bonding electrons in a covalent bond
2.14
know that ionic and covalent bonding are the extremes of a continuum of bonding type and that electronegativity differences lead to bond polarity in bonds and molecules
2.15
understand that molecules with polar bonds may not be polar molecules and be able to predict whether or not a given molecule is likely to be polar
2.16
understand the nature of intermolecular forces resulting from the following interactions:
i
London forces, instantaneous dipole-induced dipole
ii
permanent dipoles
iii
hydrogen bonds
2.17
understand the interactions in molecules, such as H2O, liquid NH3 and liquid HF, which give rise to hydrogen bonding
2.18
understand the following anomalous properties of water resulting from hydrogen bonding:
i
its relatively high melting temperature and boiling temperature
ii
the density of ice compared to that of water
2.19
be able to predict the presence of hydrogen bonding in molecules analogous to those mentioned above
2.20
understand, in terms of intermolecular forces, physical properties shown by materials, including:
i
the trends in boiling temperatures of alkanes with increasing chain length
ii
the effect of branching in the carbon chain on the boiling temperatures of alkanes
iii
the relatively low volatility, higher boiling temperatures, of alcohols compared to alkanes with a similar number of electrons
iv
the trends in boiling temperatures of the hydrogen halides, HF to HI
2.21
understand factors that influence the choice of solvents, including:
i
water, to dissolve some ionic compounds, in terms of the hydration of the ions
ii
water, to dissolve simple alcohols, in terms of hydrogen bonding
iii
water, as a poor solvent for compounds, to include polar molecules such as halogenoalkanes, in terms of inability to form hydrogen bonds
iv
non-aqueous solvents, for compounds that have similar intermolecular forces to those in the solvent
2.22
know that metallic bonding is the strong electrostatic attraction between metal ions and the delocalised electrons
Practical
Possible practicals: investigating the migration of ions, for example in a U-tube of copper(II) chromate, and seeing the effect of a charged rod on a flow of water.
2B: Structure
2.23
know that giant lattices are present in:
i
ionic solids, giant ionic lattices
ii
covalently bonded solids, such as diamond, graphite and silicon(IV) oxide, giant covalent lattices
iii
solid metals, giant metallic lattices
2.24
know that the structure of covalently bonded substances such as iodine, I2, and ice, H2O, is simple molecular
2.25
know the different structures formed by carbon atoms, including graphite, diamond and graphene
2.26
be able to predict the type of structure and bonding present in a substance from numerical data and/or other information
2.27
be able to predict the physical properties of a substance, including melting and boiling temperature, electrical conductivity and solubility in water, in terms of:
i
the types of particle present, atoms, molecules, ions, electrons
ii
the structure of the substance
iii
the type of bonding and the presence of intermolecular forces, where relevant