3.1.1

Naming Conventions

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Formulae

There are multiple kinds of formula that we use to represent molecules. They all give different information about a molecule.

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Empirical formulae

  • An empirical formula is the simplest whole number ratio of atoms in a molecule.
    • E.g. CH3 is the empirical formula of ethane.
    • E.g. CH is the empirical formula of benzene.
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Molecular formulae

  • The molecular formula of a compound gives the number of each type of atom in a molecule.
    • E.g. C2H6 is the molecular formula of ethane.
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Structural formulae

  • The structural formula is a written one-line formula showing which groups are connected to which.
    • E.g. CH3CH3 is the structural formula of ethane.
    • E.g. CH3CH2CH2CH3 is the structural formula of butane.
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Displayed formulae

  • A displayed formula is a diagram which shows every bond in a molecule.
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Skeletal formulae

  • A skeletal formula is a simplified displayed formula.
    • Hydrogen atoms are not shown and carbon atoms are at the corners of any lines.
    • A skeletal formula shows the 'skeleton' of the molecule, hence the name.

IUPAC rules

Molecules are named following the internationally-recognised IUPAC rules. The rules for naming compounds is known as 'nomenclature'.

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Name stem

  • The stem of a name is the first part of the name. It is decided by the number of carbon atoms:
    • 1 carbon → meth-
    • 2 carbons → eth-
    • 3 carbons → prop-
    • 4 carbons → but-
    • 5 carbons → pent-
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Name ending

  • The functional group gives the ending to the name.
    • Carboxylic acid: → Propanoic acid.
    • Alcohol: → ethanol.
    • Ketone: → propanone.
    • Aldehyde: → ethanal.
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Complex molecules

  • Most molecules are more complex. This means they have multiple functional groups or side chains.
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Naming conventions

  • The molecule is always named after the longest possible carbon chain that includes the functional group.
  • The carbons are numbered to give the functional group the lowest number possible.
  • Side chains are written as prefixes to the name.
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An example

  • The molecule shown above is 4-methyl-hexan-1-ol, NOT 2-methyl-hexan-6-ol or 4-ethyl-pentan-1-ol.
  • First, count the longest chain.
    • This gives a hexanol.
    • Put the alcohol at the lowest number.
    • Now name the position of the side chain.
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Rings

  • For molecules that contain rings, add 'cyclo-' at the start of the name:
    • E.g. Cyclohexane.
    • E.g. Cyclohexanol.
    • E.g. Cyclohexanone.

Homologous Series

A homologous series is a set of compounds with the same functional group. Members of a homologous series have very similar properties because they have the same functional group.

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General formulae

  • Every homologous series has its own general formula:
    • E.g. Alkanes: CnH2n+2
    • E.g. Alkenes: CnH2n
    • E.g. Alcohols: CnH2n+1OH
  • The general formula gives the molecular formula for each compound in the homologous series.
  • Different molecules in the series differ mainly in the length of their aliphatic chains.
    • Aliphatic chains are carbon chains that do not have a benzene ring.
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Functional groups

  • A functional group is a group of atoms that characterise the chemistry of a molecule. Functional groups cause specific reactions to happen with certain reagents.
  • Examples of functional groups are:
    • Hydroxyl group (-OH).
    • Carboxylic acid group (-COOH) (pictured).
    • Carbon-carbon double bond (C=C).
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Alkyl group

  • An alkyl group is a saturated hydrocarbon chain attached to a molecule.
    • The letter R can be used to represent alkyl groups.
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Aliphatic

  • Aliphatic compounds contain carbon chains that do not involve a benzene ring.
  • Aliphatic chains can be saturated, unsaturated, straight, branched or circular.
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Alicyclic

  • Alicyclic compounds are aliphatic compounds that have non-aromatic rings but no side chains.
    • E.g. Cyclohexane.
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Aromatic

  • Aromatic compounds contain at least one benzene ring.
  • Benzene rings tend to make these compounds smell.
    • This is why these compounds are described as aromatic.
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Saturated/unsaturated

  • Saturated compounds contain single bonds only between carbon atoms (C-C).
  • Unsaturated compounds contain at least one different carbon-carbon bond such as C=C or an aromatic ring.

Jump to other topics

1Physical Chemistry

1.1Atoms, Molecules & Stoichiometry

1.1.1Relative Masses

1.1.2The Mole

1.1.3Mass Spectrometry

1.1.4Empirical & Molecular Formulae

1.1.5Balanced Equations

1.1.6Molar Volume

1.1.7End of Topic Test - Amount of Substance

1.2Atomic Structure

1.2.1Fundamental Particles

1.2.2Isotopes & Mass Number

1.2.3Electron Shells, Sub-Shells & Orbitals

1.2.4Electron Configuration

1.2.5Ionisation Energy

1.2.6Factors Affecting Ionisation Energies

1.2.7Trends of Ionisation

1.2.8Specific Impacts on Ionisation Energies

1.2.9Electron Affinity

1.2.10End of Topic Test - Atomic Structure

1.2.11A-A* (AO2/3) - Atomic Structure

1.3Chemical Bonding

1.3.1Ionic Bonding

1.3.2Covalent & Dative Bonding

1.3.3Shapes of Molecules

1.3.4Intermolecular Forces

1.3.5Intermolecular Forces 2

1.3.6Electronegativity

1.3.7Bond Length, Bond Energy, & Bond Polarity

1.3.8Metallic Bonding

1.3.9Physical Properties

1.3.10End of Topic Test - Bonding

1.3.11A-A* (AO2/3) - Bonding

1.4States of Matter

1.4.1Simple Covalent Molecules

1.4.2The Ideal Gas Equation

1.4.3States of Matter

1.4.4Particle Diagrams

1.4.5The Liquid State

1.4.6Giant Ionic Lattices

1.4.7Giant Metallic Lattices

1.4.8Giant Covalent Structures

1.4.9Graphene & Fullerene

1.4.10Recycling

1.5Chemical Energetics

1.5.1Calorimetry

1.5.2Bond Enthalpies

1.5.3Enthalpy Changes

1.5.4Hess' Law

1.5.5Born-Haber Cycles

1.5.6Born-Haber Cycle Calculations

1.5.7Entropy

1.5.8Free Energy

1.5.9End of Topic Test - Energetics

1.6Electrochemistry

1.6.1Electrochemical Cells

1.6.2Electrochemical Series

1.6.3Commercial Application

1.6.4Nernst Equation

1.6.5Redox

1.7Equilibria

1.7.1Dynamic Equilibrium & Le Chatelier

1.7.2Kc

1.7.3Kp

1.7.4pH

1.7.5The Ionic Product of Water

1.7.6Weak Acids & Bases

1.7.7Introduction to Solubility Equilibria

1.7.8Solubility Equilibria Calculations

1.7.9Free Energy of Dissolution

1.7.10pH and Solubility

1.7.11Common-Ion Effect

1.7.12End of Topic Test - Kp & Electrochemistry

1.7.13A-A* (AO2/3) - Electrochemical Cells

1.8Partition Coefficient

1.8.1Kpc

1.9Reaction Kinetics

1.9.1Collision Theory

1.9.2Orders, Rate Constants & Equations

1.9.3Rate Graphs

1.9.4Rate Determining Step

1.9.5Maxwell-Boltzmann Distribution

1.9.6Catalysts

1.9.7Homogeneous Catalysts

1.9.8Heterogeneous Catalysts

1.9.9End of Topic Test - Kinetics

1.9.10End of Topic Test - Rate Equations

1.9.11A-A* (AO2/3) - Rate Equations

2Inorganic Chemistry

2.1The Periodic Table

2.1.1The Periodic Table

2.1.2Trends in the Periodic Table

2.1.3End of Topic Test - Periodicity & Trends

2.1.4Ceramics

2.1.5Period 3 Elements & Oxides

2.1.6Period 3 Oxides

2.1.7End of Topic Test - Period 3

2.2Group 2

2.2.1Group 2 Chemistry

2.3Group 17

2.3.1Introduction to Halogens

2.3.2Reactions of Halogens

2.3.3Chlorine & Chlorate(I)

2.3.4End of Topic Test - Group 17

2.3.5A-A* (AO2/3) - Periodicity, Group 2 & 17

2.4Transition Metals

2.4.1General Properties

2.4.2Titrations

2.4.3Shapes of Complex Ions

2.4.4Variable Oxidation States

2.4.5Ligands

2.4.6Colours of Ions

2.4.7Stereoisomerism of Complex Ions

2.4.8Cisplatin

2.4.9Ligand Substitutions & Kstab

2.4.10End of Topic Test - Transition Metals

2.4.11A-A* (AO2/3) - Transition Metals

2.5Nitrogen & Sulfur

2.5.1Nitrogen & Ammonia

2.5.2Formulated vs Manure Fertilisers

2.5.3Nitrogen Containing Fertilisers

2.5.4Fertilizers & Eutrophication

2.5.5Common Atmospheric Pollutants & Their Properties

2.5.6Catalytic Converters

2.5.7Atmospheric Oxides

3Organic Chemistry & Analysis

3.1Introduction to Organic Chemistry

3.1.1Naming Conventions

3.1.2Mechanism

3.1.3Isomerism

3.1.4End of Topic Test - Introduction to Organic Chem

3.2Hydrocarbons

3.2.1Fractional Distillation

3.2.2Cracking

3.2.3Combustion

3.2.4Chlorination

3.2.5End of Topic Test - Alkanes

3.2.6Introduction to Alkenes

3.2.7Reactions of Alkenes

3.2.8Polymerisation Reactions

3.2.9End of Topic Test - Alkenes

3.2.10Arenes

3.2.11Evidence for Structure of Arenes

3.2.12Reactions of Benzene

3.2.13End of Topic Test -Arenes

3.3Halogen Derivatives

3.3.1Properties of Haloalkanes

3.3.2Substitution Reactions of Haloalkanes

3.3.3Environmental Impacts of Haloalkanes

3.3.4End of Topic Test - Halogenoalkanes

3.4Hydroxy Compounds

3.4.1Types of Alcohol

3.4.2Oxidation 1

3.4.3Oxidation 2

3.4.4Elimination

3.4.5Acids & Esters

3.4.6Acyl Chlorides & Acylation

3.4.7Phenols & Their Reactions

3.4.8End of Topic Test - Alcohols

3.5Carbonyl Compounds

3.5.1Carbonyls

3.5.2Hydrogen Bonding & Carbonyls

3.5.3Aldehydes & Ketones

3.5.4Tri-Iodomethane Reaction

3.5.5End of Topic Test -Carbonyls

3.6Carboxylic Acids & Derivatives

3.6.1Properties of Carboxylic Acids

3.6.2Esters

3.6.3Acyl Chlorides

3.6.4End of Topic Test - Carboxylic Acids

3.7Nitrogen Compounds

3.7.1Nature & Preparation of Amines

3.7.2Basicity & Nucleophilicity

3.7.3Amides

3.7.4Reactions of Amino Acids

3.7.5Amino Acids

3.8Polymerisation

3.8.1Properties of Addition Polymers

3.8.2Condensation Polymerisation

3.8.3Effects of Side-Chains on Polymers

3.8.4Hydrolysis of Ester & Amide Groups

3.8.5Proteins

3.8.6DNA

3.8.7Adhesive & Conducting Polymers

3.8.8End of Topic Test - Amines & Proteins

3.9Analytical Techniques

3.9.1Chromatography

3.9.2High-Performance Liquid Chromatography

3.9.3Gas Chromatography

3.9.4IR Spectroscopy

3.9.5Uses of IR Spectroscopy

3.9.6Mass Spectrometry

3.9.7Mass Spectrometry Analysis

3.9.8Nuclear Magnetic Resonance

3.9.9Carbon-13 NMR

3.9.10Proton NMR I

3.9.11Proton NMR II

3.9.12End of Topic Test - Analytical Techniques

3.9.13A-A* (AO2/3) - Analytical Techniques

3.10Organic Synthesis

3.10.1Chirality & Drug Synthesis

3.10.2Organic Synthesis

3.10.3Examples of Synthetic Routes

3.10.4End of Topic Test - Organic Synthesis

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Atmospheric Oxides

Mechanism