A Level Chemistry examination is very different from what the O level chemistry examination was based on. For all students sitting for their A Level chemistry examination are expected to study more topics, and gain more content in a detailed manner.
If you are a student struggling to study for your upcoming A Level Chemistry, worry not! There are plenty of ways that Tutopiya can help you to ace your exam.
When it comes to preparing for your Cambridge IGCSE Chemistry exam, it is crucial to keep answering practice question papers.
Tutopiya has compiled a detailed A Level Chemistry summary notes with most of the key concepts covered. This summary note consists of all the topics tested for the Cambridge GCE A Level (excluding extension topics).
The topics include:
– Matter
– Structure and properties
– Gaseous state
– Theory of acids and bases
– Periodic Table
– Mole concept and Stoichiometry
– Chemical Engertics: Thermochemistry and Thermodynamics
– Activation Energy
– Chemical Equilibria
We have also included 10 questions based on the topic – The Particulate Nature of Matter, along with its answers for all students to be more familiar as to how to answer all question papers.
A Level Chemistry summary notes (concise version)
Matter
Atoms consist of three basic particles: protons, electrons, and neutrons. The nucleus (centre) of the atom contains the protons (positively charged) and the neutrons (no charge). The outermost regions of the atom are called electron shells and contain the electrons (negatively charged). Atoms have different properties based on the arrangement and number of their basic particles.
Behaviour of protons, neutrons, and electrons in electric field
If a beam containing each of these particles is passed between two electrically charged plates—one positive and one negative—the following are observed:
– Protons are positively charged and are thus deflected on a curving path towards the negative plate.
– Electrons are negatively charged and are deflected on a curving path towards the positive plate.
– Neutrons have no charge and continue in a straight line.
Distribution of mass and charges within an atom
Since the nucleus contains protons and neutrons, most of the mass of an atom is concentrated in its nucleus. Protons and electrons have electrical charges that are equal and opposite.
Shapes of Orbital Chemistry (shapes of s, p and d orbitals)
There are four different kinds of orbitals, denoted s, p, d and f each with a different shape. Of the four, s and p orbitals are considered because these orbitals are the most common in organic and biological chemistry.
An s-orbital is spherical with the nucleus at its centre, a p-orbitals is dumbbell-shaped, and four of the five d orbitals are cloverleaf shaped.
The fifth d orbital is shaped like an elongated dumbbell with a doughnut around its middle.
The orbitals in an atom are organized into different layers or electron shells.
Successive ionisation energies
First ionisation energy is defined as the amount of energy required to remove one mole of electron from each atom in a mole gaseous atom producing one mole of gaseous cations.
Structure and properties
Chemical bonding: is lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds.
The bond may result from the electrostatic force of attraction between oppositely charged ions as in ionic bonds or through the sharing of electrons as covalent bonds.
4 types of chemical bonding
1 – Ionic bonding
It is the complete transfer of valence electrons between atoms. It is a type of chemical bond that generates two oppositely charged ions.
2 – Metallic bonding
This force holds atoms together in a metallic substance.
3 – Covalent bonding
It is a chemical bond that involves the sharing of electron pairs between atoms.
4 – Dative covalent bonding
Also known as coordinate bond in which both electrons come from the same atom. The atoms are held together because the electron pair attracted by both the nuclei.
Bonding and physical properties
Chemical bonds are the electrical forces of attraction that hold atoms or ions together to form molecules.
Gaseous State
The ideal gas law states that PV = nRT, where P is the absolute pressure of a gas, V is the volume it occupies, N is the number of atoms and molecules in the gas, and T is its absolute temperature.
Theory of acids and bases
There are multiple definitions of acids and bases. The narrowest definition is the Arrhenius theory definition, which is primarily concerned with aqueous solutions.
Arrhenius
An Arrhenius acid increases the concentration of H+ or H3O+ (hydronium) ions.
Brønsted-Lowry
Brønsted-Lowry acid is any species that donates a proton to another molecule.
Whereas Brønsted-Lowry base is any species that accepts a proton to another molecule.
Lewis
Acids are electron pair acceptors. Acid is able to form a covalent bond with whatever supplies the electrons. Bases are electron pair donors.
Mole concept and Stoichiometry
Chemical Energetics: Thermochemistry and Thermodynamics
There are 3 sections in Chemical Energetics, namely:
- Enthalpy Changes, ΔH
- Entropy Changes, ΔS
- Gibbs Free Energy, ΔG
Hess’s Law
Hess’s Law of Constant Heat Summation (or just Hess’s Law) states that regardless of the multiple stages or steps of a reaction, the total enthalpy change for the reaction is the sum of all changes. This law is a manifestation that enthalpy is a state function.
The heat of any reaction ΔH∘fΔHf° for a specific reaction is equal to the sum of the heats of reaction for any set of reactions which in sum are equivalent to the overall reaction.
Reaction Kinetics
In chemistry and physics, activation energy is the minimum amount of energy that must be provided to compounds to result in a chemical reaction.
Factors that affect reaction rate
1 – Reactant concentrations
2 – Surface area
3 – Pressure
4 – Temperature
5 – Presence or absence of a catalyst
6 – Nature of reactants
GCSE Chemistry – Factors Affecting the Rate of Reaction #40
Activation energy
In chemistry and physics, activation energy is the minimum amount of energy that must be provided to compounds to result in a chemical reaction.
Factors that affect reaction rate
- Reactant concentrations
- Surface area
- Pressure
- Temperature
- Presence or absence of a catalyst
- Nature of reactants
Homogeneous and heterogeneous catalysis
Catalysts can be classified into two types: homogeneous and heterogeneous. Homogeneous catalysts are those which exist in the same phase (gas or liquid ) as the reactants, while heterogeneous catalysts are not in the same phase as the reactants. Typically, heterogeneous catalysis involves the use of solid catalysts placed in a liquid reaction mixture.
Heterogeneous catalysis is catalysis where the phase of catalysts differs from that of the reactants or products. The process contrasts with homogeneous catalysis where the reactants, products and catalyst exist in the same phase.
Heterogeneous catalysis is very important because it enables faster, large-scale production and the selective product formation.
Enzymes as biological catalysts
Enzymes are proteins functioning as catalysts that speed up reactions by lowering the activation energy. A simple and succinct definition of an enzyme is that it is a biological catalyst that accelerates a chemical reaction without altering its equilibrium. … In the overall process, enzymes do not undergo any net change.
A Level Chemistry summary notes (full version) for download
Sample Questions
Q1. State the distinguishing properties of solids, liquids and gases
- The three states of matter are solid, liquid and gas
- Melting and freezing take place at the melting point
- Boiling and condensing take place at the boiling point
- They can be represented by the simple model above, particles are represented by small solid spheres
- Solids- particles have a regular arrangement and are close together
- Liquids- particles have a random arrangement and are close together
- Gases- particles have a random arrangement and are spread apart
Q2. Describe the structure of solids, liquids and gases in terms of particle separation arrangement and types of motion
- Gas: particles have the most energy – shown by the diagram, as the particles are the most spread apart, motion is more random and frequent
- Liquid: particles have more energy than those in a solid, but less than those in a gas
- Solid has the least energy – particles are not moving/are just vibrating
Q3. Describe changes of state in terms of melting, boiling, evaporation, freezing, condensation and sublimation
- Physical changes – therefore involves the forces between the particles of the substances, instead of these changes of state being chemical changes.
– Evaporation = happens at the surface, molecules have enough energy to evaporate – i.e. go from liquid to gas
– Freezing = liquid to solid
– Melting = solid to liquid
– Boiling = happens throughout the liquid, liquid to gas
– Condensation = gas to liquid
– Sublimation = solid to gas
Q4. Explain changes of state in terms of the kinetic theory
Kinetic theory can help to explain melting, boiling, freezing and condensing
– The amount of energy needed to change state from solid to liquid and from liquid to gas depends on the strength of the forces between the particles of the substance
– The nature of the particles involved depends on the type of bonding and the structure of the substance.
– The stronger the forces between the particles the higher the melting point and boiling point of the substance.
– The more kinetic energy (from increased temperature) particles have, the more movement, which causes a change of state from (s) to (l) to (g)
Q5. Describe qualitatively the pressure and temperature of a gas in terms of the motion of its particles
- The higher the pressure = the more motion of a gas’ particles
- The higher the temperature = the more motion of a gas’ particles
Q6. Show an understanding of the random motion of particles in a suspension (sometimes known as Brownian motion) as evidence for the kinetic particle (atoms, molecules or ions) model of matter.
- Particles in liquids and gases (known as fluids) move randomly (this is called Brownian motion)
- This happens because they collide with other moving particles in the fluid
- This is evidence for the kinetic particle model of matter- it shows that there are individual particles that make up solids/liquids/gases
Q7. Describe and explain Brownian motion in terms of random molecular bombardment
- Particles in liquids and gases move randomly because they are bombarded by the other moving particles in the fluid. Larger particles can be moved by light, fast-moving molecules
Q8. State evidence for Brownian motion
- Robert Brown observed the random movement of pollen grains within the water, which showed that there were separate particles within the water that were moving randomly and caused the grain to move (kinetic theory)
Q9. Describe and explain diffusion
- Movement of particles from an area of high concentration to an area of low concentration
- For this to work, particles must be able to move. Therefore, diffusion does not occur in solids, since the particles cannot move from place to place (only vibrate). A smell does not travel very fast, because the particles collide with particles of air, changing direction randomly when they collide, taking much longer to travel from place to place.
Q10: Describe and explain the dependence of the rate of diffusion on molecular mass
- The smaller the molecular mass, the greater the average speed of the molecules (but all gases have the same average kinetic energy at the same temperature). Therefore, the smaller the molecular mass, the faster the gas diffuses.
