GCSE
Chemistry
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Introduction to GCSE Chemistry (AQA) Coming soon
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1.1 Atomic Structure, Elements, Compounds, and Mixtures
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1.2 The Periodic Table Coming soon
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2.1 Chemical Bonds, Ionic, Covalent and Metallic Coming soon
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2.2 How Bonding and Structure are Related to the Properties of Substances Coming soon
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2.3 Structure and Bonding of Carbon Coming soon
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2.4 Bulk and Surface Properties of Matter including Nanoparticles Coming soon
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3.1 Chemical Measurements, Conservation of Mass and the Quantitative Interpretation of Chemical Equations Coming soon
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3.2 Use of Amount of Substance in Relation to Masses of Pure Substances Coming soon
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3.3 Yield and Atom Economy of Chemical Reactions Coming soon
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3.4 Using Concentrations of Solutions in mol/dm³ [HT] Coming soon
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3.5 Use of Amount of Substance in Relation to Volumes of Gases [HT] Coming soon
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4.1 Reactivity of Metals Coming soon
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4.2 Reactions of Acids Coming soon
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4.3 Electrolysis Coming soon
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5.1 Exothermic and Endothermic Reactions Coming soon
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5.2 Chemical Cells and Fuel Cells Coming soon
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6.1 Rate of Reaction Coming soon
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6.2 Reversible Reactions and Dynamic Equilibrium Coming soon
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6.2.1 Reversible Reactions
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6.2.2 Energy Changes and Reversible Reactions
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6.2.3 Equilibrium
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6.2.4 The Effect of Changing Conditions on Equilibrium (HT only)
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6.2.5 The Effect of Changing Concentration (HT only)
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6.2.6 The Effect of Temperature Changes on Equilibrium (HT only)
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6.2.7 The Effect of Pressure Changes on Equilibrium (HT only)
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6.2.1 Reversible Reactions
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7.1 Carbon Compounds as Fuels and Feedstock Coming soon
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7.2 Reactions of Alkenes and Alcohols Coming soon
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7.3 Synthetic and Naturally Occurring Polymers Coming soon
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8.1 Purity, Formulations and Chromatography Coming soon
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8.2 Identification of Common Gases Coming soon
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8.3 Identification of Ions by Chemical and Spectroscopic Means Coming soon
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9.1 The Composition and Evolution of the Earth's Atmosphere Coming soon
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9.2 Carbon Dioxide and Methane as Greenhouse Gases Coming soon
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9.3 Common Atmospheric Pollutants and their Sources Coming soon
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10.1 Using the Earth's Resources and Obtaining Potable Water Coming soon
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10.2 Life Cycle Assessment and Recycling Coming soon
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10.3 Using Materials Coming soon
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10.4 The Haber Process and the use of NPK Fertilisers Coming soon
1. Atomic Structure and the Periodic Table
1.1.1 Atoms, Elements and Compounds
In this lesson, you will learn how atoms make up all substances and how different types of atoms form elements. You will explore chemical symbols and the periodic table, discover how atoms bond to form compounds, and understand how chemical reactions are represented using word and balanced symbol equations.
Atoms, Elements and their Symbols
Every object or substance around us is made of very very small particles called atoms. There are different types of atoms which we call elements. You can also think of elements as substances made of only one type of atom. You are likely already familiar with many elements like iron, gold and oxygen.

Different elements have different properties, for example iron and gold are solids at room temperature, while oxygen is a gas. We represent atoms of each element with a unique one or two letter symbol called a chemical symbol, a few examples of which you can see in Figure 1. We can also refer to chemical symbols as atomic symbols. All the elements that we know of and their chemical symbols can be found in the periodic table, shown below in Figure 2.

The periodic table shown in Figure 1 above will be the one you are given in your exam, so make sure you are familiar with it!Note
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Create a free accountAtoms, Elements and their Symbols
- An atom is a very small particle that makes up all substances.
- Elements are substances made of only one type of atom.
- Atoms of each element are represented by a unique one or two letter symbol called a chemical symbol.
- The periodic table shows all the known elements.
Compounds and their Formulas
- Compounds are substances made from two or more atoms chemically bonded to each other.
- The forces that hold atoms in a compound together are called chemical bonds.
- Compounds are represented by formulas that combine the symbols of the elements from which the compounds are made of.
- In a compound, the atoms of each element are in fixed proportions.
- The properties of a compound are often very different from the properties of the original elements.
Chemical Reactions and Chemical Equations
- Chemical reactions are the processes that create chemical bonds between atoms to make compounds and break chemical bonds between atoms to break compounds.
- Chemical reactions always form one or more new substances.
- Chemical reactions always happen with a change in energy.
- Chemical reactions can be represented in two ways: word equations and symbol equations.
- Symbol equations must always be balanced to make sure there are the same number of atoms on both sides of the equation.
