A substance is a type of matter with uniform properties throughout. This means that a sample of a substance will have the same characteristics regardless of its size.
- One kind of substance is a chemical substance. A chemical substance is a specific type of matter with molecules that share the same structure and composition.
- These molecules are held together by chemical bonds. Substances cannot be separated into their component parts (elements or compounds) without breaking these chemical bonds.
- Substances can be generally classified into two main categories:
- Elements: The simplest form of a substance, elements are made up of only one type of atom.
- Compounds: These substances are formed when two or more elements chemically bond together.
- The properties of a substance, such as melting point, boiling point, and density, are unique and can be used to identify the substance and distinguish it from other substances. Chemical reactions involve the formation and breaking of these chemical bonds, transforming one or more substances into different substances with new properties.