11.1.1

Formula of a Molecule

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Formula of a Molecule

A molecular formula shows the number and type of atoms in a molecule, while a displayed formula also shows how the atoms are bonded together.

Molecular formula

Molecular formula

A molecular formula shows the number and type of atoms in a molecule.
For example:
- Water → H₂O (2 hydrogen atoms, 1 oxygen atom)
- Carbon dioxide → CO₂ (1 carbon atom, 2 oxygen atoms)

Displayed formula

Displayed formula

A displayed formula shows all the atoms and all the covalent bonds in a molecule.
- Each bond is represented by a single line.
This is different from a chemical formula which only shows the number and type of atoms.
Displayed formulae are useful for showing the structure of more complex molecules.

Examples of displayed formulae

Examples of displayed formulae

Water (H₂O) has 2 hydrogen atoms and 1 oxygen atom.
The oxygen atom is at the centre, with a single bond to each of the hydrogen atoms.

Examples of displayed formulae 2

Examples of displayed formulae 2

Ethane (C₂H₆) contains two carbon atom and six hydrogen atoms.
They are connected by seven single bonds:
- A line between the two carbon atoms
- Six single lines between the carbon and each hydrogen atom

Interpreting a displayed formula

Interpreting a displayed formula

A displayed formula helps:
- Identify the atoms: Count how many of each type of atom are present
- Identify the bonds: Count the number of bonds to see how the atoms are linked
For example, using the displayed formula for methane (CH₄) shows one carbon atom and four hydrogen atoms, connected by four single bonds.
This makes it easier to see differences between similar molecules.

1

States of Matter

1.1

Solids, Liquids, & Gases

1.1.1States of Matter - Solids, Liquids & Gases 1.1.2Structure of Solids, Liquids & Gases 1.1.3Changes of State 1.1.4The Effects of Temperature & Pressure 1.1.5Kinetic Theory 1.1.6Kinetic Theory - Effects of Temperature & Pressure

1.2

Diffusion

1.2.1Diffusion 1.2.2The Effect of Relative Molecular Mass

2

Atoms, Elements & Compounds

2.1

Elements, Compounds & Mixtures

2.1.1Differences Between Elements, Compounds & Mixtures

2.2

Atomic Structure & the Periodic Table

2.2.1The Structure of the Atom 2.2.2Relative Charge, Mass & Atomic Numbers 2.2.3Electronic Configuration of Elements

2.3

Isotopes

2.3.1Isotopes 2.3.2Electronic Configuration of Isotopes 2.3.3Calculating Relative Atomic Mass

2.4

Ions & Ionic Bonds

2.4.1Properties of Ionic Compounds - Structure & Bond 2.4.2Formation of Ions & Ionic Bonds 2.4.3Formation of Ionic Bonds - Metals & Non-Metals 2.4.4Ionic Bonds 2.4.5Ionic Compounds 2.4.6Giant Lattice Structure of Ionic Compounds

2.5

Simple Molecules & Covalent Bonds

2.5.1Covalent Bonds 2.5.2Formation of Covalent Bonds 2.5.3Structure & Properties of Simple Molecules 2.5.4Covalent Bonds in Simple Molecules 2.5.5Properties of Simple Molecular Compounds

2.6

Giant Covalent Structures

2.6.1Giant Covalent Structures - Graphite 2.6.2Giant Covalent Structures - Diamond 2.6.3Uses of Graphite & Diamonds 2.6.4Giant Covalent Structures - Silicon Oxide 2.6.5Similarity Between Diamond & Silicon Oxide

2.7

Metallic Bonding

2.7.1Metallic Bonding 2.7.2The Properties of Metals

3

Stoichometry

3.1

Formulae

3.1.1Understanding Formulae 3.1.2Empirical Formula 3.1.3Stoichiometry - Formulae, Word & Symbol Equations 3.1.4Deduce & Write Ionic Compound Formulas

3.2

Relative Masses of Atoms & Molecules

3.2.1Relative Atomic Mass 3.2.2Relative Molecular Mass (Mr)3.2.3Calculating Reacting Masses

3.3

The Mole & the Avogadro Constant

3.3.1Introducing Moles 3.3.2Amounts of Substances 3.3.3Moles & Equations 3.3.4Calculations Involving Gases 3.3.5Calculating Stoichiometric Reacting Masses 3.3.6Calculating the Moles of Solute 3.3.7Calculating Empirical Formula 3.3.8Chemical Equations 3.3.9Percentage Yield 3.3.10Calculating Yield 3.3.11Percentage Purity

4

Electrochemistry

4.1

Electrolysis

4.1.1Electrolytic Process 4.1.2Electrolysis Examples 4.1.3Electrolysis of a Binary Compound in Molten State 4.1.4Electroplating 4.1.5Transfer of Charge During Electrolysis 4.1.6Electrolysis of Aqueous Solutions 4.1.7Electrolysis of Copper Sulfate 4.1.8Electrolysis of Halide Compounds 4.1.9Half-Equations 4.1.10Combustion of Hydrocarbons

4.2

Hydrogen–Oxygen Fuel Cells

4.2.1Fuel Cells 4.2.2Hydrogen Fuel Cells 4.2.3Comparing Hydrogen-Oxygen Fuel Cells & Petrol

5

Chemical Energetics

5.1

Exothermic & Endothermic Reactions

5.1.1Energy Conservation 5.1.2Exothermic Reactions 5.1.3Endothermic Reactions 5.1.4Energy Change of a Reaction 5.1.5Reaction Pathway Diagrams 5.1.6Calculating Enthalpy Change

6

Chemical Reactions

6.1

Physical & Chemical Changes

6.1.1Difference btwn Physical & Chemical Changes

6.2

Rate of Reaction

6.2.1Collision Theory & Rate of Reaction 6.2.2Factors Affecting Rate of Reaction 6.2.3Investigating Rate of Reaction by Change in Mass 6.2.4Investigating Rate - Formation of a Gas 6.2.5Evaluating Methods to Investigate Reaction Rates

6.3

Reversible Reactions & Equilibrium

6.3.1Reversible Reactions 6.3.2Conditions & Equilibrium 6.3.3Dynamic Equilibrium 6.3.4Changing Conditions - Heat & Water Effects 6.3.5Factors Affecting Equilibria - Temperature 6.3.6Factors Affecting Equilibria - Pressure 6.3.7Factors Affecting Equilibria - Concentration 6.3.8The Haber Process 6.3.9The Haber Process Equation

6.4

Redox

6.4.1Redox Reactions 6.4.2Redox Reactions - OIL RIG 6.4.3Examples of Redox Reactions 6.4.4Identifying Redox Reactions 6.4.5Identifying Redox Reactions by Colour Changes 6.4.6Testing for Oxidising & Reducing Agents

7

Acids, Bases & Salts

7.1

The Characteristic Properties of Acids & Bases

7.1.1Acids & Alkali 7.1.2Reactions of Metals with Acids 7.1.3Reactions of Bases with Acids 7.1.4Reactions of Carbonates with Acids 7.1.5Identifying Acids 7.1.6Properties & Effects of Acids 7.1.7Properties of Bases - Reactions with Acids & Salts 7.1.8Properties of Alkalis & Indicators 7.1.9Strong vs Weak Acids 7.1.10Strong vs Weak Bases 7.1.11Understanding Universal Indicator Paper 7.1.12Acids, Bases & the Neutralisation Reaction

7.2

Oxides

7.2.1Oxides 7.2.2Amphoteric Oxides - Reacting with Acids & Bases

7.3

Preparation of Salts

7.3.1Soluble Salts 7.3.2Preparing Soluble Salts 7.3.3Solubility of Salts 7.3.4Preparing Insoluble Salts & Crystallisation

8

The Periodic Table

8.1

Arrangement of Elements

8.1.1The Periodic Table 8.1.2Metals & Non-Metals

8.2

Group I Properties

8.2.1Alkali Metals 8.2.2Alkali Metals - Properties 8.2.3Reactivity of Alkali Metals 8.2.4Alkali Metals & Water

8.3

Group VII Properties

8.3.1The Halogens - Properties 8.3.2The Halogens - Colours & States 8.3.3The Halogen - Displacement 1 8.3.4The Halogen - Displacement 2

8.4

Transition Elements

8.4.1Transition Metals 8.4.2Transition Metals - Special Properties

8.5

Noble Gases

8.5.1Noble Gases - Properties

9

Metals

9.1

Properties of Metals

9.1.1Physical Properties of Metals 9.1.2Chemical Properties of Metals 9.1.3Metal Oxides

9.2

Uses of Metals

9.2.1Uses of Metals: Aluminium & Copper

9.3

Alloys & Their Properties

9.3.1Alloys 9.3.2Alloys 2 9.3.3Alloys & their Uses in Everyday Life 9.3.4Structural Diagrams of Alloys 9.3.5Structure of Alloys & Their Strength

9.4

Reactivity Series

9.4.1Metals - Reactivity Series & Reactivity 9.4.2Order of Reactivity 9.4.3Reactivity of Metals

9.5

Corrosion of Metals

9.5.1Corrosion 9.5.2Preventing Corrosion

9.6

Extraction of Metals

9.6.1Extraction of Metals 9.6.2Extracting Iron 9.6.3Extracting Aluminium from Bauxite

10

Chemistry of the Environment

10.1

Water

10.1.1Testing & Treating Water 10.1.2Testing Water Purity Using Melting Point 10.1.3Water from Natural Sources 10.1.4Potable Water

10.2

Fertilisers

10.2.1Nitrogen & Fertilisers

10.3

Air Quality & Climate

10.3.1Gases in the Atmosphere 10.3.2Common Atmospheric Pollutants 10.3.3Consequences of Atmospheric Pollutants 10.3.4Strategies to Reduce Pollution Effects 10.3.5Photochemical Reactions 10.3.6Car Engines, Nitrogen Oxides, & Converters

11

Organic Chemistry

11.1

Formulae, Functional Groups & Terminology

11.1.1Formula of a Molecule 11.1.2General Formulae of Organic Compounds 11.1.3Functional Groups 11.1.4Homologous Series 11.1.5Saturated & Unsaturated Organic Compounds 11.1.6Structural Formula 11.1.7Structural Isomers

11.2

Naming Organic Compounds

11.2.1Drawing Displayed Formulae 11.2.2Naming Organic Compounds - Unbranched 11.2.3Naming Unbranched Esters from Alcohols & Acids 11.2.4Naming Structural Formulae

11.3

Fuels

11.3.1Fossil Fuels 11.3.2Methane as the Main Constituent of Natural Gas 11.3.3Fuels & Hydrocarbons 11.3.4Petroleum - A Mixture of Hydrocarbons 11.3.5Fractional Distillation 11.3.6Fractions 11.3.7Uses of Fractions - Fuels

11.4

Alkanes

11.4.1Alkanes 11.4.2Properties of Alkanes 11.4.3Substitution Reactions of Alkanes with Chlorine

11.5

Alkenes

11.5.1Alkenes 11.5.2Shortest Alkenes 11.5.3Reactions of Alkenes 11.5.4Types of Alkene Reactions 11.5.5Cracking 11.5.6Testing Saturated & Unsaturated Hydrocarbons 11.5.7Properties of Alkenes - Addition Reactions

11.6

Alcohols

11.6.1Alcohols 11.6.2Smallest Alcohols 11.6.3Fermentation 11.6.4Steam 11.6.5Fermentation vs Hydration of Ethene 11.6.6Manufacture of Ethanol: Fermentation & Hydration 11.6.7Combustion of Ethanol 11.6.8Uses of Ethanol - Solvent & Fuel 11.6.9Advantages & Disadvantages of Ethanol Manufacture

11.7

Carboxylic Acids

11.7.1Carboxylic Acids 11.7.2Smallest Carboxylic Acids 11.7.3Reactions of Carboxylic Acids 11.7.4Formation of Ethanoic Acid

11.8

Polymers

11.8.1Polymers 11.8.2Problems With Polymers 11.8.3Polymers & Plastics 11.8.4Problems with Plastics 11.8.5Condensation Polymerisation 11.8.6Condensation Polymerisation Examples 11.8.7Addition Polymerisation 11.8.8Addition Polymerisation Examples 11.8.9Structure of Polymers 11.8.10Natural Polyamides - Proteins & Amino Acids

12

Experimental Techniques & Chemical Analysis

Jump to other topics

1

States of Matter

1.1

Solids, Liquids, & Gases

1.1.1States of Matter - Solids, Liquids & Gases 1.1.2Structure of Solids, Liquids & Gases 1.1.3Changes of State 1.1.4The Effects of Temperature & Pressure 1.1.5Kinetic Theory 1.1.6Kinetic Theory - Effects of Temperature & Pressure

1.2

Diffusion

1.2.1Diffusion 1.2.2The Effect of Relative Molecular Mass

2

Atoms, Elements & Compounds

2.1

Elements, Compounds & Mixtures

2.1.1Differences Between Elements, Compounds & Mixtures

2.2

Atomic Structure & the Periodic Table

2.2.1The Structure of the Atom 2.2.2Relative Charge, Mass & Atomic Numbers 2.2.3Electronic Configuration of Elements

2.3

Isotopes

2.3.1Isotopes 2.3.2Electronic Configuration of Isotopes 2.3.3Calculating Relative Atomic Mass

2.4

Ions & Ionic Bonds

2.4.1Properties of Ionic Compounds - Structure & Bond 2.4.2Formation of Ions & Ionic Bonds 2.4.3Formation of Ionic Bonds - Metals & Non-Metals 2.4.4Ionic Bonds 2.4.5Ionic Compounds 2.4.6Giant Lattice Structure of Ionic Compounds

2.5

Simple Molecules & Covalent Bonds

2.5.1Covalent Bonds 2.5.2Formation of Covalent Bonds 2.5.3Structure & Properties of Simple Molecules 2.5.4Covalent Bonds in Simple Molecules 2.5.5Properties of Simple Molecular Compounds

2.6

Giant Covalent Structures

2.6.1Giant Covalent Structures - Graphite 2.6.2Giant Covalent Structures - Diamond 2.6.3Uses of Graphite & Diamonds 2.6.4Giant Covalent Structures - Silicon Oxide 2.6.5Similarity Between Diamond & Silicon Oxide

2.7

Metallic Bonding

2.7.1Metallic Bonding 2.7.2The Properties of Metals

3

Stoichometry

3.1

Formulae

3.1.1Understanding Formulae 3.1.2Empirical Formula 3.1.3Stoichiometry - Formulae, Word & Symbol Equations 3.1.4Deduce & Write Ionic Compound Formulas

3.2

Relative Masses of Atoms & Molecules

3.2.1Relative Atomic Mass 3.2.2Relative Molecular Mass (Mr)3.2.3Calculating Reacting Masses

3.3

The Mole & the Avogadro Constant

3.3.1Introducing Moles 3.3.2Amounts of Substances 3.3.3Moles & Equations 3.3.4Calculations Involving Gases 3.3.5Calculating Stoichiometric Reacting Masses 3.3.6Calculating the Moles of Solute 3.3.7Calculating Empirical Formula 3.3.8Chemical Equations 3.3.9Percentage Yield 3.3.10Calculating Yield 3.3.11Percentage Purity

4

Electrochemistry

4.1

Electrolysis

4.1.1Electrolytic Process 4.1.2Electrolysis Examples 4.1.3Electrolysis of a Binary Compound in Molten State 4.1.4Electroplating 4.1.5Transfer of Charge During Electrolysis 4.1.6Electrolysis of Aqueous Solutions 4.1.7Electrolysis of Copper Sulfate 4.1.8Electrolysis of Halide Compounds 4.1.9Half-Equations 4.1.10Combustion of Hydrocarbons

4.2

Hydrogen–Oxygen Fuel Cells

4.2.1Fuel Cells 4.2.2Hydrogen Fuel Cells 4.2.3Comparing Hydrogen-Oxygen Fuel Cells & Petrol

5

Chemical Energetics

5.1

Exothermic & Endothermic Reactions

5.1.1Energy Conservation 5.1.2Exothermic Reactions 5.1.3Endothermic Reactions 5.1.4Energy Change of a Reaction 5.1.5Reaction Pathway Diagrams 5.1.6Calculating Enthalpy Change

6

Chemical Reactions

6.1

Physical & Chemical Changes

6.1.1Difference btwn Physical & Chemical Changes

6.2

Rate of Reaction

6.2.1Collision Theory & Rate of Reaction 6.2.2Factors Affecting Rate of Reaction 6.2.3Investigating Rate of Reaction by Change in Mass 6.2.4Investigating Rate - Formation of a Gas 6.2.5Evaluating Methods to Investigate Reaction Rates

6.3

Reversible Reactions & Equilibrium

6.3.1Reversible Reactions 6.3.2Conditions & Equilibrium 6.3.3Dynamic Equilibrium 6.3.4Changing Conditions - Heat & Water Effects 6.3.5Factors Affecting Equilibria - Temperature 6.3.6Factors Affecting Equilibria - Pressure 6.3.7Factors Affecting Equilibria - Concentration 6.3.8The Haber Process 6.3.9The Haber Process Equation

6.4

Redox

6.4.1Redox Reactions 6.4.2Redox Reactions - OIL RIG 6.4.3Examples of Redox Reactions 6.4.4Identifying Redox Reactions 6.4.5Identifying Redox Reactions by Colour Changes 6.4.6Testing for Oxidising & Reducing Agents

7

Acids, Bases & Salts

7.1

The Characteristic Properties of Acids & Bases

7.1.1Acids & Alkali 7.1.2Reactions of Metals with Acids 7.1.3Reactions of Bases with Acids 7.1.4Reactions of Carbonates with Acids 7.1.5Identifying Acids 7.1.6Properties & Effects of Acids 7.1.7Properties of Bases - Reactions with Acids & Salts 7.1.8Properties of Alkalis & Indicators 7.1.9Strong vs Weak Acids 7.1.10Strong vs Weak Bases 7.1.11Understanding Universal Indicator Paper 7.1.12Acids, Bases & the Neutralisation Reaction

7.2

Oxides

7.2.1Oxides 7.2.2Amphoteric Oxides - Reacting with Acids & Bases

7.3

Preparation of Salts

7.3.1Soluble Salts 7.3.2Preparing Soluble Salts 7.3.3Solubility of Salts 7.3.4Preparing Insoluble Salts & Crystallisation

8

The Periodic Table

8.1

Arrangement of Elements

8.1.1The Periodic Table 8.1.2Metals & Non-Metals

8.2

Group I Properties

8.2.1Alkali Metals 8.2.2Alkali Metals - Properties 8.2.3Reactivity of Alkali Metals 8.2.4Alkali Metals & Water

8.3

Group VII Properties

8.3.1The Halogens - Properties 8.3.2The Halogens - Colours & States 8.3.3The Halogen - Displacement 1 8.3.4The Halogen - Displacement 2

8.4

Transition Elements

8.4.1Transition Metals 8.4.2Transition Metals - Special Properties

8.5

Noble Gases

8.5.1Noble Gases - Properties

9

Metals

9.1

Properties of Metals

9.1.1Physical Properties of Metals 9.1.2Chemical Properties of Metals 9.1.3Metal Oxides

9.2

Uses of Metals

9.2.1Uses of Metals: Aluminium & Copper

9.3

Alloys & Their Properties

9.3.1Alloys 9.3.2Alloys 2 9.3.3Alloys & their Uses in Everyday Life 9.3.4Structural Diagrams of Alloys 9.3.5Structure of Alloys & Their Strength

9.4

Reactivity Series

9.4.1Metals - Reactivity Series & Reactivity 9.4.2Order of Reactivity 9.4.3Reactivity of Metals

9.5

Corrosion of Metals

9.5.1Corrosion 9.5.2Preventing Corrosion

9.6

Extraction of Metals

9.6.1Extraction of Metals 9.6.2Extracting Iron 9.6.3Extracting Aluminium from Bauxite

10

Chemistry of the Environment

10.1

Water

10.1.1Testing & Treating Water 10.1.2Testing Water Purity Using Melting Point 10.1.3Water from Natural Sources 10.1.4Potable Water

10.2

Fertilisers

10.2.1Nitrogen & Fertilisers

10.3

Air Quality & Climate

10.3.1Gases in the Atmosphere 10.3.2Common Atmospheric Pollutants 10.3.3Consequences of Atmospheric Pollutants 10.3.4Strategies to Reduce Pollution Effects 10.3.5Photochemical Reactions 10.3.6Car Engines, Nitrogen Oxides, & Converters

11

Organic Chemistry

11.1

Formulae, Functional Groups & Terminology

11.1.1Formula of a Molecule 11.1.2General Formulae of Organic Compounds 11.1.3Functional Groups 11.1.4Homologous Series 11.1.5Saturated & Unsaturated Organic Compounds 11.1.6Structural Formula 11.1.7Structural Isomers

11.2

Naming Organic Compounds

11.2.1Drawing Displayed Formulae 11.2.2Naming Organic Compounds - Unbranched 11.2.3Naming Unbranched Esters from Alcohols & Acids 11.2.4Naming Structural Formulae

11.3

Fuels

11.3.1Fossil Fuels 11.3.2Methane as the Main Constituent of Natural Gas 11.3.3Fuels & Hydrocarbons 11.3.4Petroleum - A Mixture of Hydrocarbons 11.3.5Fractional Distillation 11.3.6Fractions 11.3.7Uses of Fractions - Fuels

11.4

Alkanes

11.4.1Alkanes 11.4.2Properties of Alkanes 11.4.3Substitution Reactions of Alkanes with Chlorine

11.5

Alkenes

11.5.1Alkenes 11.5.2Shortest Alkenes 11.5.3Reactions of Alkenes 11.5.4Types of Alkene Reactions 11.5.5Cracking 11.5.6Testing Saturated & Unsaturated Hydrocarbons 11.5.7Properties of Alkenes - Addition Reactions

11.6

Alcohols

11.6.1Alcohols 11.6.2Smallest Alcohols 11.6.3Fermentation 11.6.4Steam 11.6.5Fermentation vs Hydration of Ethene 11.6.6Manufacture of Ethanol: Fermentation & Hydration 11.6.7Combustion of Ethanol 11.6.8Uses of Ethanol - Solvent & Fuel 11.6.9Advantages & Disadvantages of Ethanol Manufacture

11.7

Carboxylic Acids

11.7.1Carboxylic Acids 11.7.2Smallest Carboxylic Acids 11.7.3Reactions of Carboxylic Acids 11.7.4Formation of Ethanoic Acid

11.8

Polymers

11.8.1Polymers 11.8.2Problems With Polymers 11.8.3Polymers & Plastics 11.8.4Problems with Plastics 11.8.5Condensation Polymerisation 11.8.6Condensation Polymerisation Examples 11.8.7Addition Polymerisation 11.8.8Addition Polymerisation Examples 11.8.9Structure of Polymers 11.8.10Natural Polyamides - Proteins & Amino Acids

12

Experimental Techniques & Chemical Analysis

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Car Engines, Nitrogen Oxides, & Converters

General Formulae of Organic Compounds