Edexcel International A Level Chemistry
Topic 3
Bonding
& Structure
Topic 3 explains how particles are held together and how bonding affects structure and properties. This topic covers ionic bonding, covalent bonding, molecular shapes, bond polarity, electronegativity, metallic bonding and the relationship between structure and physical behaviour.
Exam Unit
Unit 1
WCH11/01 – IAS
Specification Points
3.1 – 3.22
22 points covered
Topic Parts
4 parts
Revision notes available
Exam Board
Edexcel IAL
Pearson International
Revision Notes
Ions and lattices
Ionic
Bonding
Bonding
1
Available
Ionic Bonding & Structure
Ion formation, dot-and-cross diagrams, ionic lattices, electrostatic attraction, ionic radii and polarisation.
Start revisingShared electrons
Covalent
Bonds
Bonds
2
Available
Covalent Bonding & Structure
Covalent attraction, dot-and-cross diagrams, dative covalent bonds, carbon structures, electronegativity and polarity.
Start revisingElectron pairs
Molecular
Shapes
Shapes
bond angles and 3D arrangement
3
Available
Shapes of Molecules
Electron-pair repulsion theory, bond angles, bond lengths and predicting the shapes of molecules and ions.
Start revising4
Available
Metallic Bonding & Structure
Giant metallic lattices, delocalised electrons, electrical conductivity and high melting temperatures.
Start revising5
Available
Structure Types
Giant ionic, giant metallic, giant covalent and simple molecular lattices compared: what holds each together and how that decides its properties.
Start revisingSpecification Coverage
Topic 3 Bonding & Structure – Edexcel International A Level Chemistry
The following specification points outline the knowledge and skills students are expected to demonstrate for Topic 3.
3A: Ionic Bonding
3.1
know and be able to interpret evidence for the existence of ions, limited to physical properties of ionic compounds, electron density maps and the migration of ions
3.2
be able to describe the formation of ions in terms of loss or gain of electrons
3.3
be able to draw dot-and-cross diagrams to show electrons in cations and anions
3.4
be able to describe ionic crystals as giant lattices of ions
3.5
know that ionic bonding is the result of strong net electrostatic attraction between ions
3.6
understand the effects of ionic radius and ionic charge on the strength of ionic bonding
3.7
understand reasons for the trends in ionic radii down a group in the Periodic Table, and for a set of isoelectronic ions, including N3- to Al3+
3.8
understand the meaning of the term polarisation as applied to ions
3.9
understand that the polarising power of a cation depends on its radius and charge, and the polarisability of an anion also depends on its radius and charge
Practical
Further suggested practical: The migration of ions in a U-tube using copper(II) chromate solution or on a microscope slide using potassium manganate(VII) crystals.
3B: Covalent Bonding
3.10
understand that covalent bonding is the strong electrostatic attraction between two nuclei and the shared pair of electrons between them, based on the evidence:
i
the physical properties of giant atomic structures
ii
electron density maps for simple molecules
3.11
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 with dative covalent, coordinate, bonds, including Al2Cl6 and the ammonium ion
3.12
be able to describe the different structures formed by giant lattices of carbon atoms, including graphite, diamond and graphene, and discuss the applications of each
3.13
understand the meaning of the term electronegativity as applied to atoms in a covalent bond
3.14
know that ionic and covalent bonding are the extremes of a continuum of bonding type and be able to explain this in terms of electronegativity differences, leading to bond polarity in bonds and molecules, and to ionic bonding if the electronegativity is large enough
3.15
be able to distinguish between polar bonds and polar molecules and predict whether or not a given molecule is likely to be polar
Practical
Further suggested practical: Determine the effect of an electrostatic force on jets of liquids, water, ethanol and cyclohexane, and use the results to determine whether the molecules are polar or non-polar.
3C: Shapes of Molecules
3.16
understand the principles of the electron-pair repulsion theory, used to interpret and predict the shapes of simple molecules and ions
3.17
understand the terms bond length and bond angle
3.18
know and be able to explain the shapes of, and bond angles in, BeCl2, BCl3, CH4, NH3, NH4+, H2O, CO2, gaseous PCl5, SF6 and C2H4
3.19
be able to apply the electron-pair repulsion theory to predict the shapes of, and bond angles in, molecules and ions analogous to those in 3.18
3D: Metallic Bonding
3.20
understand that metals consist of giant lattices of metal ions in a sea of delocalised electrons
3.21
know that metallic bonding is the strong electrostatic attraction between metal ions and the delocalised electrons
3.22
be able to use the models in 3.20 and 3.21 to interpret simple properties of metals, including electrical conductivity and high melting temperature
Specification Coverage
Topic 3 Bonding & Structure – Edexcel International A Level Chemistry
The following specification points outline the knowledge and skills students are expected to demonstrate for Topic 3.
3A: Ionic Bonding
3.1
know and be able to interpret evidence for the existence of ions, limited to physical properties of ionic compounds, electron density maps and the migration of ions
3.2
be able to describe the formation of ions in terms of loss or gain of electrons
3.3
be able to draw dot-and-cross diagrams to show electrons in cations and anions
3.4
be able to describe ionic crystals as giant lattices of ions
3.5
know that ionic bonding is the result of strong net electrostatic attraction between ions
3.6
understand the effects of ionic radius and ionic charge on the strength of ionic bonding
3.7
understand reasons for the trends in ionic radii down a group in the Periodic Table, and for a set of isoelectronic ions, including N3- to Al3+
3.8
understand the meaning of the term polarisation as applied to ions
3.9
understand that the polarising power of a cation depends on its radius and charge, and the polarisability of an anion also depends on its radius and charge
Practical
Further suggested practical: The migration of ions in a U-tube using copper(II) chromate solution or on a microscope slide using potassium manganate(VII) crystals.
3B: Covalent Bonding
3.10
understand that covalent bonding is the strong electrostatic attraction between two nuclei and the shared pair of electrons between them, based on the evidence:
i
the physical properties of giant atomic structures
ii
electron density maps for simple molecules
3.11
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 with dative covalent, coordinate, bonds, including Al2Cl6 and the ammonium ion
3.12
be able to describe the different structures formed by giant lattices of carbon atoms, including graphite, diamond and graphene, and discuss the applications of each
3.13
understand the meaning of the term electronegativity as applied to atoms in a covalent bond
3.14
know that ionic and covalent bonding are the extremes of a continuum of bonding type and be able to explain this in terms of electronegativity differences, leading to bond polarity in bonds and molecules, and to ionic bonding if the electronegativity is large enough
3.15
be able to distinguish between polar bonds and polar molecules and predict whether or not a given molecule is likely to be polar
Practical
Further suggested practical: Determine the effect of an electrostatic force on jets of liquids, water, ethanol and cyclohexane, and use the results to determine whether the molecules are polar or non-polar.
3C: Shapes of Molecules
3.16
understand the principles of the electron-pair repulsion theory, used to interpret and predict the shapes of simple molecules and ions
3.17
understand the terms bond length and bond angle
3.18
know and be able to explain the shapes of, and bond angles in, BeCl2, BCl3, CH4, NH3, NH4+, H2O, CO2, gaseous PCl5, SF6 and C2H4
3.19
be able to apply the electron-pair repulsion theory to predict the shapes of, and bond angles in, molecules and ions analogous to those in 3.18
3D: Metallic Bonding
3.20
understand that metals consist of giant lattices of metal ions in a sea of delocalised electrons
3.21
know that metallic bonding is the strong electrostatic attraction between metal ions and the delocalised electrons
3.22
be able to use the models in 3.20 and 3.21 to interpret simple properties of metals, including electrical conductivity and high melting temperature