Chemical Equations

Equations in chemistry are used to describe a chemical reaction. Word equations use the element or compound names, while chemical equations use element symbols.

Everything that is at the start of the reaction is on the left-hand side and is known as the reactants.

Everything that is produced during the reaction is on the right-hand side and is known as the products.

Did you also notice that there was something odd about the names of the compounds? Instead of writing magnesium chlorine (as per the element names), chlorine was changed to chloride!

Rules for Writing Equations

1. Determine which element comes first in the compound name.

   The element furthest to the left on the periodic table goes first.

2. In a compound made of two elements, the second element name changes its ending, -ide replaces the -ine suffix. Oxygen is also included here, whenever oxygen appears at the end of a binary compound, change the ending to -ide. e.g. oxide

Rules for Writing Equations

3. Sometimes we use a common name for a compound instead of its full name, e.g. water, hydrogen peroxide, hydrochloric acid, methane, and ammonia.

4. There are some pieces of compounds that are seen quite often. Similar to how we change the name to end in -ide, they have their own endings

Who's Sigma?

When forming a compound using the elements carbon and oxygen, which would appear first?

You undertake an activity where you combine zinc metal with hydrochloric acid.

The products are zinc chloride and hydrogen gas. Write out the word equation for this reaction.

Try to guess the word equation:

You undertake an activity where you combine zinc metal with hydrochloric acid.

The products are zinc chloride and hydrogen gas. Write out the word equation for this reaction.

Answer:

zinc + hydrochloric acid → zinc chloride + hydrogen