Writing chemical equations

• Chemistry
• Secondary Education

TEMPLATE

Topic 6 - Formulae and Equations

Chemical Equations

12 November 2025

How do you feel today?

😒🙁😐🙂😃

TEMPLATE

• I will be able to write the following equations given the chemical reaction:
  - word equation

    - symbol equation

    - state symbols ( s ), ( l ), ( g ), ( aq )

• I will be able to carry out experiments to investigate the types of reactions.

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Which of the following are the reactants? products?

Which of the following are the reactants? products?

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How do we make writing the reactions easier and more understandable?

Chemical reactions change substances into other substances.

A chemical equation is used to represent a reaction. 

Chemical equations have the form:          reactants → products

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Types of chemical reactions

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Types of chemical equations

Word Equation: We use the names of substances

Symbol Equation (with state symbols): We use the formulae 

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Types of chemical equations

Word Equation: We use the names of substances

Symbol Equation (with state symbols): We use the formulae 

Example:

Reaction: Nitrogen and hydrogen gases react together to form liquid ammonia.

Word Equation:          

Symbol equation:

TEMPLATE

Work in groups: Carry out three experiments to investigate the types of chemical reactions

Experiment 1 – Combustion Reaction (Burning)

Complete combustion = with enough oxygen

Incomplete combustion = with less oxygen

Experiment 2 – Decomposition Reaction

Thermal decomposition = use of heat

Electrolytic decomposition = use of electricity

Photolytic decomposition = use of light

Experiment 3 – Single Displacement Reaction and Synthesis Reaction

TEMPLATE

• I will be able to write the following equations given the chemical reaction:
  - word equation

    - symbol equation

    - state symbols ( s ), ( l ), ( g ), ( aq )

• I will be able to carry out experiments to investigate the types of reactions.

How well did you participate 

in the lesson today?

05

TEMPLATE

Will you follow the same method in writing the formulae of covalent compounds?

Example:

            a molecule of carbon and oxygen

Symbol:

Valency:

Formulae:

1. Use the name to identify the atoms present.
2. Write the valency for each.
3. Swap the valencies. 
4. Simplify if they will both divide by the same number.

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What if you are given these?

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Work individually: 

Do Activity 5 of your LAP sheets.

TEMPLATE

• I will know how to write the formulae of ionic and covalent compounds.
• I will understand why models and diagrams are important in writing the formulae of compounds.

How well did you participate 

in the lesson today?

05

TEMPLATE

Presents a new problem or scenario that requires students to apply their knowledge. For instance, after studying ecosystems, the teacher might ask students to explore the effects of an oil spill.

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Assesses student comprehension through a worksheet, quiz, a lab report, or a concluding class discussion.

How well did you enjoy the lesson today?

05

sample

TEMPLATE

• I will know how to write the formulae of ionic and covalent compounds.
• I will understand why models and diagrams are important in writing the formulae of compounds.
• I will be able to write the molecular and empirical formulae of compounds.