Atoms Molecules and Elements

• Reaction between two or more elements, resulting in the formation of a chemical bond between atoms and the formation of a chemical compound either by releasing or consuming energy can be represented by formula of entities.

Thus a chemical equation is a short form that is used to describe a chemical reaction.

• The substances that undergo the change are called reactants and the substances that are formed as a result of chemical change are called products.

Example:

Carbon burns in air to form carbon dioxide gas releasing heat in the process.

Carbon is the reactant. Carbon dioxide is the product. Heat energy is released in the conversion.

• A chemical equation conveys important information about a chemical reaction.
• The reactants and products are shown using their symbols and formulae.
• Besides this, special symbols are used to give important information.
• The special symbols used in a chemical equation are:

Special symbols used in chemical equations: