Chemistry
This page is for students studying the AQA Chemistry course at Kings. It contains a number of useful documents, links and additional reading that will support your independent learning throughout your course. If you have arrived here from another School you are most welcome to follow the links listed here to support your learning!
Please note that this page is being regularly updated, and more information should appear here during 2020-2021
Useful Course Documents (links)
AQA Chemistry Practical Skills Handbook
AQA Chemistry subject specific vocabulary
If you are wondering what comes up in which exam, you see this in the specification document here on page 9
Year 11 - Preparing for A-Level Chemistry
If you have just finished Y11, and as we are School due to Covid-19 restrictions, there are a number of tasks that you can do in order to get your level of understanding up to where it should be for starting the AQA A-level course at Kings. Obviously your understanding of Chemistry should be at grade 7 or above, but really we need to lift your comprehension to a bit more than that, if you’re really ready to engage with the material in Y12. You should start by re-capping the GCSE course in full which is actually best described on the BBC Bitesize website. Particularly atomic structure, bonding and redox.
Physical Chemistry
3.1.1 Atomic structure
The chemical properties of elements depend on their atomic structure and in particular on the arrangement of electrons around the nucleus. The arrangement of electrons in orbitals is linked to the way in which elements are organised in the Periodic Table. Chemists can measure the mass of atoms and molecules to a high degree of accuracy in a mass spectrometer. The principles of operation of a modern mass spectrometer are studied.
3.1.1.1 Fundamental particles
You will need to appreciate that knowledge and understanding of atomic structure has evolved over time as you did and GCSE. Also know the relative charge and relative mass of subatomic particles (Protons, neutrons and electrons)
3.1.1.2 Mass number and Isotopes
The principles of a simple time of flight (TOF) a mass spectrometer, limited to ionisation, acceleration to give all ions constant kinetic energy, ion drift, ion detection, data analysis
Further information can be found here
https://filestore.aqa.org.uk/resources/chemistry/AQA-7404-7405-SG-TOFMS-QA.PDF
https://filestore.aqa.org.uk/resources/chemistry/AQA-7404-7405-SG-TOFMS.PDF
3.1.1.3 Electron Configuration
Build on GCSE Electron configurations of atoms and ions up to Z = 36 using the terms shells and sub-shells (orbitals) s, p and d.
Define first ionisation energy, write equations and explain how first and successive ionisation energies in Period 3 (Na–Ar) and in Group 2 (Be–Ba) give evidence for electron configuration in sub-shells and in shells
3.1.2 Amount of substance
For now, you should ensure you can carry out the GCSE calculations involving moles, mass and concentrations
3.1.3 Bonding
You will have studied Ionic, covalent and metallic bonding at GCSE, did you really understand this? It is vital to A-level. You can review these ideas on BBC Bitesize
3.1.3.1 Ionic bonding
Ionic bonding involves electrostatic attraction between oppositely charged ions in a lattice. You will have to write the formulas of compounds with ions eg sulfate, hydroxide, nitrate, carbonate and ammonium.
3.1.3.2 Nature of Covalent and dative Covalent bonds
Be able to define covalent bonds as - single covalent bond contains a shared pair of electrons. Multiple bonds contain multiple pairs of electrons.
A co-ordinate (dative covalent) bond contains a shared pair of electrons with both electrons supplied by one atom.
3.1.3.3 Metallic bonding
Metallic bonding involves attraction between delocalised electrons and positive ions arranged in a lattice.
3.1.3.4 Bonding and Physical Properties
Recognise and draw the structures, relate properties and explain energy changes linked to change of state for the following crystals as examples of these four types of crystal structure:
Diamond, Graphite, Ice, Iodine, Magnesium
3.1.3.5 Shapes of simple molecules and Ions
Explain, using VSEPR, the shapes of, and bond angles in, simple molecules and ions with up to six electron pairs (including lone pairs of electrons) surrounding the central atom. There is a useful chart here
3.1.3.6 Bond Polarity
Define Electronegativity as the power of an atom to attract the pair of electrons in a covalent bond.
Explain how polar bonds create permanent dipole within molecules.
3.1.3.7 Forces Between Molecules
Explain how the melting and boiling points of molecular substances are influenced by the strength of these intermolecular forces.
permanent dipole–dipole forces
induced dipole–dipole (van der Waals, dispersion, London) forces hydrogen bonding.
Organic chemistry
3.3.1 Introduction to organic chemistry
Organic chemistry is the study of the millions of covalent compounds of the element carbon. These structurally diverse compounds vary from naturally petroleum fuels to DNA and the molecules in living systems.
Organic compounds also demonstrate human ingenuity in the vast range of synthetic materials created by chemists. Many of these compounds are used as drugs, medicines and plastics.
Organic mechanisms are studied, which enable reactions to be explained. In the search for sustainable chemistry, for safer agrochemicals and for new materials to match the desire for new technology, chemistry plays the dominant role.
3.3.2 Alkanes
Alkanes are the main constituent of crude oil, which is an important raw material for the chemical industry. Alkanes are also used as fuels and the environmental consequences of this use are considered in this section.
Alkanes are saturated hydrocarbons. Petroleum is a mixture consisting mainly of alkane hydrocarbons that can be separated by fractional distillation.
Cracking involves breaking C–C bonds in alkanes. Thermal cracking takes place at high pressure and high temperature and produces a high percentage of alkenes (mechanism not required). Catalytic cracking takes place at a slight pressure, high temperature and in the presence of a zeolite catalyst and is used mainly to produce motor fuels and aromatic hydrocarbons (mechanism not required). Students should be able to explain the economic reasons for cracking alkanes.
Alkanes are used as fuels. Combustion of alkanes and other organic compounds can be complete or incomplete. The internal combustion engine produces a number of pollutants including NOx ,
CO, carbon and unburned hydrocarbons. Understand global warming. and some of the solutions.
These gaseous pollutants from internal combustion engines can be removed using catalytic converters. Combustion of hydrocarbons containing sulfur leads to sulfur dioxide that causes air pollution. Students should be able to explain why sulfur dioxide can be removed from flue gases using calcium oxide or calcium carbonate.
3.3.3 Halogenoalkanes
Halogenoalkanes are much more reactive than alkanes. They have many uses, including as refrigerants, as solvents and in pharmaceuticals. The use of some halogenoalkanes has been restricted due to the effect of chlorofluorocarbons (CFCs) on the atmosphere.
Ozone, formed naturally in the upper atmosphere, is beneficial because it absorbs ultraviolet radiation. Chlorine atoms are formed in the upper atmosphere when ultraviolet radiation causes C–Cl bonds in chlorofluorocarbons (CFCs) to break.
Chlorine atoms catalyse the decomposition of ozone and contribute to the hole in the ozone layer. Appreciate that results of research by different groups in the scientific community provided evidence for legislation to ban the use of CFCs as solvents and refrigerants. Chemists have now developed alternative chlorine-free compounds.
3.3.4 Alkenes
In alkenes, the high electron density of the carbon–carbon double bond leads to attack on these molecules by electrophiles. This section also covers the mechanism of addition to the double bond and introduces addition polymers, which are commercially important and have many uses in modern society.
Alkenes are unsaturated hydrocarbons. Bonding in alkenes involves a double covalent bond, a centre of high electron density.
Addition polymers are formed from alkenes and substituted alkenes. The repeating unit of addition polymers. IUPAC rules for naming addition polymers. Addition polymers are unreactive. Appreciate that knowledge and understanding of the production and properties of polymers has developed over time. Typical uses of poly(chloroethene), commonly known as PVC, and how its properties can be modified using a plasticiser. Students should be able to:
• draw the repeating unit from a monomer structure
• draw the repeating unit from a section of the polymer chain
• draw the structure of the monomer from a section of the polymer
• explain why addition polymers are unreactive
• explain the nature of intermolecular forces between molecules of polyalkenes.
3.3.5 Alcohols
Alcohols have many scientific, medicinal and industrial uses. Ethanol is one such alcohol and it is produced using different methods, which are considered in this section. Ethanol can be used as a biofuel.
Alcohols are produced industrially by hydration of alkenes in the presence of an acid catalyst. Ethanol is produced industrially by fermentation of glucose. The conditions for this process. Ethanol produced industrially by fermentation is separated by fractional distillation and can then be used as a biofuel. Students should be able to:
• explain the meaning of the term biofuel
• justify the conditions used in the production of ethanol by fermentation of glucose
• write equations to support the statement that ethanol produced by fermentation is a carbon-neutral fuel and give reasons why this statement is not valid
• outline the mechanism for the formation of an alcohol by the reaction of an alkene with steam in the presence of an acid catalyst
• discuss the environmental (including ethical) issues linked to decision making about biofuel use.
Alcohols are classified as primary, secondary and tertiary. Primary alcohols can be oxidised to aldehydes which can be further oxidised to carboxylic acids. Secondary alcohols can be oxidised to ketones. Tertiary alcohols are not easily oxidised. Acidified potassium dichromate(VI) is a suitable oxidising agent.
Alkenes can be formed from alcohols by acid-catalysed elimination reactions. Alkenes produced by this method can be used to produce addition polymers without using monomers derived from crude oil. Students should be able to outline the mechanism for the elimination of water from alcohols.
3.3.6 Organic analysis
Our understanding of organic molecules, their structure and the way they react, has been enhanced by organic analysis. This section considers some of the analytical techniques used by chemists, including test-tube reactions and spectroscopic techniques.
Students should be able to identify the functional groups using reactions in the specification.
Mass spectrometry can be used to determine the molecular formula of a compound. Students should be able to use precise atomic masses and the precise molecular mass to determine the molecular formula of a compound.
Bonds in a molecule absorb infrared radiation at characteristic wavenumbers. ‘Fingerprinting’ allows identification of a molecule by comparison of spectra.