Representing Chemical Reactions

Understanding Chemical Reactions

A chemical reaction involves the breaking and forming of chemical bonds between different substances to create new ones.
Reactants are the starting substances, and products are the substances that are formed.
All chemical reactions are represented by chemical equations.

A chemical equation shows the reactants and products in a chemical reaction.
The reactants are written on the left, the products are written on the right, and an arrow separates them (→), which can be read as “yields” or “forms”.
Each substance is represented by its chemical symbol or formula. For example, for the burning of methane, the equation is: CH4 + 2O2 → CO2 + 2H2O
If more than one molecule is required, this is indicated by a number in front of the chemical formula.

Balance is a key principle in a chemical equation represented by an equal number of atoms of each element on both sides of the equation.
This relates to the law of conservation of mass which states that matter cannot be created or destroyed. Therefore, all atoms present in the reactants must also be present in the products.

To provide more information about the substances involved in the reaction, state symbols are often included in chemical equations.
State symbols represent the physical states of the substances at the reaction conditions: (s) for solid, (l) for liquid, (g) for gas, (aq) for aqueous (substances dissolved in water).
They are important because substances in different states can behave differently in a reaction.

The ability to understand and predict products from chemical reactions is a fundamental part in learning about chemical reactions.
This requires knowledge on various types of reactions like combination, decomposition, displacement, and redox reactions among others.
Prediction takes practice and can initially be difficult, but gets easier with repetition and familiarity with common reactants and products.