Chemistry Revision
Kinetic Particle Theory & States of Matter
Solids
Solid: Fixed volume, shape, and mass; particles vibrate in fixed positions.
 Strong forces of attraction
 Particles arranged orderly
 Vibrate only; no translation
 High density, incompressible
 Fixed melting point indicates purity
Liquids
Liquid: Fixed volume, no fixed shape; particles slide past each other.
 Weaker forces than solids
 Irregular particle pattern
 Adapt to container shape
 Fixed volume (particles still close)
Gases
Gas: No fixed shape or volume; particles move randomly (Brownian motion).
 Negligible attractive forces
 Random motion (Brownian motion)
 Volume changes with pressure and temperature
 Pressure ∝ collision frequency with walls
State Changes & Phase Diagrams
Change
Direction
Melting
Freezing
Boiling
Condensation
Evaporation
solid → liquid
liquid → solid
liquid → gas
gas → liquid
liquid → gas (surface
only)
solid ⇌ gas (direct)
Sublimation
Energy
Flow
absorb
release
absorb
release
absorb
—
Key Notes
Fixed temperature = melting point
Same temperature as melting
Bubbles throughout; fixed boiling point
Can occur over temperature range
Below boiling point; rate increases with surface area
and temperature
e.g. iodine; fixed temperature
Diffusion & Purity
Diffusion
Movement from high → low concentration due to random particle motion.
 Rate decreases with larger molecular mass
 Rate increases with temperature
Purity Indicators
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Fixed melting and boiling points
Impurities:
o Increase boiling point (liquid)
o Decrease melting point (solid)
Atomic Structure & the Periodic Table
Sub-atomic Particles
Particle Charge Relative Mass
Proton +1
1
Neutron 0
1
Electron −1
≈ 1/1840
Key Definitions
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Atomic number = proton count → fixes periodic position
Nucleon number = protons + neutrons
Neutrons = nucleon number − proton number
Isotopes: same Z, different N → same chemistry, different mass
Electron Shells & Stability
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Shell capacities: 1st = 2 e⁻, 2nd and 3rd = 8 e⁻
Valence shell = outermost shell
Noble gases = full outer shell → unreactive
Group number = number of valence electrons
Period number = number of occupied shells
Example:
4p, 3n nucleus; 4 e⁻ in outer shell → neutral atom
Bonding Types Overview
Bond
Type
Ionic
Covalent
Metallic
Particles Involved
metal cation + non-metal anion
non-metal atoms share
electrons
metal cations + delocalised
sea of electrons
Force
electrostatic high melting/boiling points, conduct when
molten or aqueous, soluble
—
low melting/boiling points, non-conductors,
insoluble
electrostatic conduct electricity, malleable, ductile, high
melting point
Macromolecules & Allotropes
Diamond
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4 covalent bonds per carbon → 3-D lattice
No free electrons → does not conduct electricity
Extremely hard, high density → cutting tools, jewellery
Graphite
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3 covalent bonds per carbon → hexagonal layers
1 free electron per carbon → conducts electricity
Weak forces between layers → slippery, lubricant, pencils
Silicon Dioxide (SiO₂)
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Typical Properties
Tetrahedral structure like diamond
High melting point, hard, non-conductive
Uses: sand, glass
Stoichiometry Essentials
The Mole
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1 mole = 6.02 × 10²³ particles
1 mole of gas = 24 dm³ at r.t.p.
Formulae
moles = mass ÷ Mᵣ
gas volume (dm³) = moles × 24
concentration (mol dm⁻³) = moles ÷ volume (dm³)
Amount of Substance
 moles = mass (g) ÷ molar mass (g/mol)
Molar Gas Volume (r.t.p.)
 volume (dm³) = moles × 24
Concentration
 concentration (mol/dm³) = moles ÷ volume (dm³)
 concentration (g/dm³) = mass (g) ÷ volume (dm³)
Number of Particles
 number of particles = moles × 6.02 × 10²³
Empirical Formula
 moles = mass ÷ Ar simplest ratio = divide all mole values by the smallest
Percentage Yield
 percentage yield = (actual yield ÷ theoretical yield) × 100
Percentage Composition by Mass
 percentage = (Ar × number of atoms ÷ Mr) × 100
Chromatography
 Rf = distance moved by substance ÷ distance moved by solvent
Energetics (Bond Energies)
 ΔH = energy of bonds broken − energy of bonds formed
Relative Formula Mass
 Mr = sum of all Ar values in the formula
Density
 density = mass ÷ volume
Gas Calculations (general)
 moles = volume (dm³) ÷ 24
Unit Conversions
 1 dm³ = 1000 cm³
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Limiting Reactant
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Reactant that is totally consumed → reaction stops
Compare mole ratios and available amounts
Percentage Yield & Purity
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% yield = (actual ÷ theoretical) × 100
% purity = (mass of pure substance ÷ total mass) × 100
Electrolysis & Electrochemistry
Cell Set-up
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Anode = positive (PANIC)
Cathode = negative
Anion → anode (oxidation)
Cation → cathode (reduction)
Battery + labelled electrodes; anions migrate to anode, cations to cathode
Products
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Molten binary compound: metal at cathode, non-metal at anode
Dilute aqueous: O₂ at anode (4OH⁻ → O₂ + 2H₂O + 4e⁻), H₂ or metal at cathode (less reactive wins)
Concentrated halide: Cl₂, Br₂, I₂ preferentially discharged at anode
Electroplating
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Anode = pure plating metal (dissolves)
Cathode = object to be plated
Electrolyte = soluble salt of plating metal
Organic Chemistry
Formulae, Functional Group and Terminology
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Organic Chemistry is the scientific study of the structure, properties, and reactions of organic carbon
compounds.
Suffix
Compound type
-ane
Alkane
-ene
Alkene
-anol
Alcohol
-anoic acid
Carbloxylic acid
-yl/-anoate
Ester
Homologous Series: a group of organic compounds that have similar chemical properties due to being part of
the:
Same Functional Group
Same General Formula
Differing from One member to the next by a CH2 unit
Displaying a trend in physical properties
Sharing similar chemical properties
Essential Terminology
1.
2.
3.
4.
Functional Group: an atom or group of atoms that determine the chemical properties of a homologous series
Structural Isomers: compounds with the same molecular formula but different structural formula.
Saturated Compounds: molecules in which all carbon-carbon bonds are single bonds.
Unsaturated Compounds: molecules where one or more carbon-carbon bonds are not single.
Fuels
Common fossil fuels include: coal, natural gas [main constituent: methane] and petroleum
Petroleum: a mixture of hydrocarbons (Carbon and Hydrogen ONLY) which can be separated into useful
fractions by fractional distillation
Going down the fractions:
 Increasing chain length
 Increasing temperature
 Lower volatility
 Increase Boiling Points
 Increase Viscosity (harder to flow)
Petroleum Fraction
Refinery gas
Gasoline fraction
Naphtha fraction
Kerosene/Paraffin fraction
Diesel oil/Gas oil fraction
Fuel oil fraction
Lubricating fraction
Bitumen
Uses
heating and cooking
fuels for cars
chemical feedstock
jet fuel
fuel in diesel engines
fuel in ships and home heating systems
lubricants, waxes and polishes
making roads
Complete & Incomplete Combustion
Methane: CH4 (n=1)
Ethane: C2H6 (n=2)
Propane: C3H8 (n=3)
Butane: C4H10 (n=4)
Complete Combustion
A complete combustion reaction with any organic compounds will produce Carbon Dioxide and Water as its
product. The general equation is:
CXHY + O2 → CO2 + H2O
Incomplete Combustion
An incomplete combustion reaction with any organic compounds will produce Carbon Monoxide and Water as its
product. The general equation is:
CXHY + O2 → CO + H2O
Alkanes
Alkanes: saturated hydrocarbons [single carbon bonds] that are generally unreactive; however, they do
undergo combustion reactions
General formula = CnH2n+2
Substitution Reaction
Alkanes go through substitutional reactions, where the atom of another element under UV light replaces the hydrogen
atom. (Photochemical)
The presence of UV light is to provide activation energy
CH4 + Cl2 → (light) → HCl + CH3Cl / CH2Cl2 / CHCl3 / CCl4
Compounds = chloromethane/di/tri/tetrachloromethane
Alkenes
Alkenes: unsaturated hydrocarbons [at least one double bond between 2 carbon atoms]
Have isomers: same molecular formula but different structural formula (placement of double bond shifts), e.g. but-1-ene
and but-2-ene
General formula = CnH2n
Functional group: C=C bond
(n=1)
Ethene:C2H4 (n=2)
N/A
Propene:C3H6 (n=3)
But-1-ene:C4H8 (n=4)
Catalytic Cracking (Alkane)
Thermal decomposition reaction at 700 Celsius, in which an alkene (and sometimes hydrogen) is produced from an
alkane. It also form shorter-chain alkanes.
Hydrocarbon is heated, and vapours are passed over a catalyst (alumina (Al2O3 and silica)
Cracking always produces a short-chain compound with a C=C bond (matches the supply of fractions with demand and
produces alkene for feedstock.)
e.g. Cracking of ethane will give ethene and hydrogen
Butane → Ethane + Ethene ; C4H10 → C2H6 + C2H4
How do we distinguish between saturated and unsaturated hydrocarbons?
Using Bromine water (reddish-brown):
Saturated: remains reddish brown (unreactive)
Unsaturated: turns colourless/decolourises
Alkenes’ Addition Reactions
Alkene addition reactions only form one product.
With Bromine: (the test for saturation - orange brown-colourless)
e.g. ethene (g) + bromine (aq) → 1,2-dibromoethane (l)
With steam (hydration): forms alcohols with heat (300°C), pressure (60atm/6000kPa) and an acid catalyst
(phosphoric acid)
e.g. ethene (g) + steam (g) ⇌ ethanol (l)
With hydrogen (hydrogenation), a double bond breaks down to form an alkane with a heat of 200 degrees and a
catalyst (nickel)
e.g. ethene (g) + hydrogen (g) → ethane (g)
Alcohols
General formula = CnH2n+1OHCnH2n+1OH
Functional group: OH
Methanol: CH3OHCH3OH (n=1)
Ethanol: C2H5OHC2H5OH (n=2)
Propanol: C3H7OHC3H7OH (n=3)
Butanol: C4H9OHC4H9OH (n=4)
Methods of Production
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Fermentation of Aqueous Glucose
(for Ethanol)
Catalytic Addition of Steam to Ethene
Yeast is added to dissolved glucose. The
products ethanol, carbon dioxide, and
the temperature between 25-35 °C are
used for optimal enzyme activity.
The ethene reacts with steam (reversibly) to form ethanol
in the following conditions: 300°C, 60 atm (6000
kPa). Catalyst - phosphoric acid [while low temp gives
better yield, high temp is used for a faster rate of
reaction]
The slow reaction produces a dilute
solution that requires processing. Can
only be produced in batches
The fast reaction produces pure ethanol. Continuous
production (no batches)
Produces greenhouse gas (CO2CO2)
No greenhouse pollutants
Uses renewable resources
Uses non-renewable resources (crude oil)
Uses of Ethanol:
Solvent in glues, printing inks & perfumes
Fuel
Carboxylic Acids
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General formula: CnH2n+1COOH
Functional group: COOH
Methanoic Acid: CH2O2 (n=0)
Propanoic Acid: C3H6O2 (n=2)
Ethanoic Acid: CH3COOH (n=1)
Butanoic acid: C4H8O2 (n=3)
Properties of Ethanoic Acid
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Weak acid with high pH and low dissociation
Formed by:
Bacterial Oxidation of Ethanol (Vinegar Production)
With acidified aqueous potassium manganateP (VII) (Good Oxidising Agent)
Carboxylic acids react with alcohols (with an acid catalyst/Heat) to give esters in a condensation reaction, for
example:
Ethanoic acid + ethanol ⇌ ethyl ethanoate + water (alcohol = -yl & carboxylic acid = -anoate)
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Carboxylic Acids also have different structural isomers.
Reactions with Carboxylic Acid
Magnesium reacts with ethanoic acid to form magnesium ethanoate and hydrogen gas.
 2CH3COOH + Mg → (CH3COO)2Mg + H2
When propanoic acid reacts with hydroxides, it will form salt and water (Neutralization reaction)
 CH3CH2COOH + KOH → CH3CH2COOK + H2O
When butanoic acid reacts with carbonates, it will form salt, water, and carbon dioxide.
 2CH3CH2CH2COOH + K2CO3 → 2CH3CH2CH2COOK + H2O + CO2
Polymers
A polymer is a very large molecule made by joining many small molecules called monomers together in a long
chain. Each monomer is a small, simple molecule that can react with others to form a polymer.
Monomers
A monomer is a single repeating unit that joins to other monomers during polymerization. Thousands of
monomers can join to form one polymer molecule.
Polymer Linkages
The atoms that join monomers together form a linkage.
The type of linkage depends on the monomers used and the type of polymerization.
 Polyesters such as PET contain ester linkages
 Polyamides such as nylon and proteins contain amide linkages
Plastics and PET
Plastics are synthetic polymers.
One common plastic is polyethylene terephthalate (PET), which is used to make bottles and containers.
Most plastics are not biodegradable, meaning microorganisms cannot break them down easily.
However, PET can be hydrolysed using heat and chemicals to break it back into its monomers. These
monomers can then be re-polymerized, which allows recycling.
Environmental Problems Caused by Plastics
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Plastics build up in landfill sites
Plastics accumulate in oceans and harm marine life
Burning plastics releases toxic and harmful gases
Poly(ethene)
Poly(ethene) is one of the most common plastics.
 Low-density poly(ethene): plastic bags, gloves, Clingfilm
 High-density poly(ethene): mugs, bowls, chairs, dustbins
Properties of Polymers
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Low density
Can be molded under heat and pressure
Poor conductors of heat and electricity
Resistant to corrosion
Non-biodegradable and create plastic waste problems
Addition Polymerization
Addition polymerization happens when monomers containing a carbon–carbon double bond, C=C, join
together.
Only alkene monomers can undergo addition polymerization.
The double bond breaks and each carbon forms a new single
bond with neighboring monomers.
Only a polymer is formed and no other products are produced.
Example:
Ethene undergoes addition polymerization to form poly(ethene).
After polymerization, the polymer contains no double bonds.
Condensation Polymerization
Condensation polymerization occurs when two different monomers join together.
Each time the monomers link, a small molecule, usually water, is removed. One water molecule is formed for
each linkage.
Nylon (polyamide) is made from a dicarboxylic acid monomer and a diamine monomer (a compound with an
NH2 functional group). Forms amide linkage.
PET (polyester) is made from a dicarboxylic acid monomer and diols (alcohol with an -OH functional group).
Forms ester linkage.
Nylon and Polyamides
Nylon is a polyamide made by condensation polymerization. It is formed from:
 A dicarboxylic acid monomer
 A diamine monomer containing the NH₂ group
When these react, an amide linkage is formed and water is released.
PET and Polyesters
PET is a polyester made by condensation polymerization. It is formed from:
 A dicarboxylic acid monomer
 A diol monomer containing two OH groups
An ester linkage forms between the monomers and water is released.
Proteins and Natural Polyamides
Proteins are natural polymers and are also polyamides. They are made from amino acid monomers.
Each amino acid contains:
 An amine group (NH₂)
 A carboxylic acid group (COOH)
 A hydrogen atom
 A variable R group
General Structure of Amino Acids:
Proteins:
Formation of Proteins
Amino acids join together by condensation polymerization.
An amide linkage forms between the amino acids.
Water is released each time a linkage is formed.
Proteins contain the same type of linkage as nylon, but they are made from biological monomers.