Direct comparison
Element vs compound
An element is a pure substance made of one kind of atom; a compound is two or more different elements chemically bonded together in fixed proportions.
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Side-by-side comparison
| Dimension | Element | Compound |
|---|---|---|
| What it is | A pure substance of one kind of atom. | Two or more elements chemically bonded together. |
| Can it be broken down chemically? | No — it is already the simplest form. | Yes — into its constituent elements. |
| Composition | Identical atoms (same atomic number). | Different elements in a fixed ratio. |
| Bonds present | May have none, or bonds between like atoms (O₂). | Chemical bonds between different elements. |
| Properties | Its own characteristic properties. | New properties, often unlike its elements. |
| Represented by | A chemical symbol (e.g. Fe, O). | A chemical formula (e.g. H₂O, NaCl). |
| On the periodic table | Each element has its own place. | Not listed — it is a combination of elements. |
| Example | Hydrogen, oxygen, iron, gold, helium. | Water (H₂O), salt (NaCl), carbon dioxide (CO₂). |
| Ratio of components | Not applicable — only one element present. | Fixed and definite (e.g. 2 H to 1 O in water). |
Both are pure substances — mixtures are different
Elements and compounds are both pure substances, meaning they have a fixed, definite composition throughout. What separates them from a mixture is that a mixture combines substances physically, in any proportion, without chemical bonding, so its parts keep their own properties and can be separated by physical means. A compound, by contrast, has its elements locked in a fixed ratio by chemical bonds, and behaves as a single new substance. Recognising that water is a compound, but salty water is a mixture, captures the distinction cleanly.
Common questions
FAQ
Can an element be broken down into anything simpler?+
Not by chemical means. An element is the simplest form of matter that ordinary chemistry can produce — it is made of just one kind of atom. You can only break an atom into protons, neutrons and electrons through nuclear or physical processes, which are outside everyday chemistry. So within chemistry, elements are the building blocks from which compounds are made.
Is water an element or a compound?+
Water is a compound. Each water molecule contains two hydrogen atoms chemically bonded to one oxygen atom, in a fixed 2:1 ratio, written H₂O. Because two different elements are joined by chemical bonds, water counts as a compound, not an element — and it can be split into hydrogen and oxygen by electrolysis.
How is a compound different from a mixture?+
A compound has its elements chemically bonded in a fixed ratio and behaves as one new substance with its own properties. A mixture combines substances physically in any proportion, with no bonding, so each component keeps its own properties and can be separated by physical methods such as filtering or evaporation. Bonding and fixed ratio are the key markers of a compound.
Going deeper
