Definition
Compounds are substances formed by the chemical bonding of two or more different elements in a fixed, definite proportion.
Why It Matters
They represent systems where elements lose their individual properties to create a completely new substance.
Core Concepts
- Compound: A substance made of two or more elements chemically combined in a fixed ratio (e.g., , ). The properties of a compound are usually entirely different from the properties of the elements that make it up.
- How to read: “The chemical formulas H two O and N a C l.”
- Meaning: Water and table salt—fixed-ratio chemical combinations whose properties differ entirely from constituent elements.
- Molecule: The smallest particle of a compound that has all the properties of the compound. Molecules are held together by chemical bonds (sharing or transferring electrons).
- Mixture: A substance that is mixed together without chemical bonding. The components of a mixture retain their original properties and can usually be separated by physical means (e.g., salt and sand, air).
- Chemical Bond: The force of attraction that holds atoms together in a compound. This is primarily an electrical force between the nuclei and the electrons of different atoms.