Substance
What is Substance?
In chemistry, a substance (pure substance) is matter with a uniform and definite composition throughout, which cannot be separated into other kinds of matter by any physical means. Pure substances are classified as either elements (composed of a single type of atom, e.g., gold, oxygen) or compounds (composed of two or more elements in a fixed ratio by mass, e.g., water, sodium chloride). Substances are distinguished from mixtures, which consist of two or more substances in variable proportions.
Key Facts
Frequently Asked Questions
In chemistry, a substance (pure substance) is matter with a uniform and definite composition throughout, which cannot be separated into other kinds of matter by any physical means. Pure substances are classified as either elements (composed of a single type of atom, e.g., gold, oxygen) or compounds (composed of two or more elements in a fixed ratio by mass, e.g., water, sodium chloride). Substances are distinguished from mixtures, which consist of two or more substances in variable proportions.