Introduction to chemical reactions - Chemical Reactions and Groups

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Introduction to chemical reactions


In this lesson, we will learn:
• How to determine whether a chemical reaction has occurred.
• The methods of writing a chemical reaction.


• Chemical reactions involve collisions between molecules – they are far too small to see directly with the naked eye. Instead we make observations which are evidence that a reaction has happened or is happening.

• For chemists, an observation would be something that we can tell directly using our senses, for example seeing a color change, feeling a temperature change (like a glass beaker warming up) or seeing gas being released from a test tube.

• The reason this happens is because different chemical compounds have different properties that we can see when that chemical is produced. For example a color change from brown to colorless might mean a reactant chemical that is brown is being converted into a product that is colorless.

• There are two ways to write that a reaction is taking place:
\circ a word equation
\circ a chemical (symbol) equation.

• The → arrow found in a chemical equation is very important; it shows that a reaction is taking place. The reactants (what gets put in) of a reaction are always on the left-hand side of it, and the products (the new chemical that gets made) of a reaction are always on the right-hand side.

  • Intro Lesson
    Introduction to chemical reactions
  • 1.
    Write word and chemical equations to describe basic chemical reactions.
    Some hydrochloric acid (HCl) was added to a beaker containing sodium hydroxide (NaOH). A reaction occurred and produced sodium chloride (NaCl) and water (H2_2O).
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Introduction to chemical reactions

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