Chemistry is an experimental physical science, concerned with the properties of and relationships between matter and energy . We may define these two fundamental manifestations of nature in the traditional way.
Matter occupies space and has mass.
A feel for energy is better obtained by trying to think of examples of things that are NOT matter. For instance, light is not matter, nor is heat. Gravity is not matter, nor is it energy. It is instead a force. Forces and energy are intimately connected, so we may view gravity as a disguised form of energy.