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What is a chemical compound?
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Quick answer
A chemical compound is a substance made of two or more different elements chemically bonded together in a fixed ratio — like water (H₂O) or table salt (NaCl). A compound has its own properties, often completely different from the elements that form it.
Key things to understand
- A compound contains at least two different elements bonded in a fixed ratio.
- Its properties differ from its elements — sodium (a reactive metal) and chlorine (a toxic gas) form harmless table salt.
- Compounds can only be separated into their elements by chemical reactions, not physical methods.
- Water (H₂O), carbon dioxide (CO₂), and table salt (NaCl) are everyday compounds.
- A compound is different from a mixture, where substances are combined but not chemically bonded.
People also ask
What's the difference between a compound and a mixture?
In a compound, elements are chemically bonded in a fixed ratio and form a new substance. In a mixture, substances are just physically combined, keep their own properties, and can be separated physically.
What's the difference between a compound and a molecule?
A molecule is two or more atoms bonded together; a compound is a molecule made of at least two different elements. So O₂ is a molecule but not a compound, while H₂O is both.
Can a compound be broken back into elements?
Yes, but only through a chemical reaction — for example, passing electricity through water splits it back into hydrogen and oxygen.