Elements, Compounds and Mixtures

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An element is a pure substance that cannot be converted further into anything simpler than itself by any physical or chemical process. All atoms in an element are identical. Example: iron, copper, alu…

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A compound is a pure substance formed by the chemical combination of two or more elements in a fixed ratio by mass. It can be broken down only by chemical means. Example: water is a compound of hydrog…

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A mixture is an impure substance formed by mixing two or more pure substances in any proportion without chemical change. The substances keep their own properties. Example: air, soil, salt solution.

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The components of a mixture are not chemically combined, so they remain separate and keep their individual properties. This makes methods like filtration, evaporation, and magnetic separation possible…

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Sodium and chlorine combine chemically to form sodium chloride, which is common salt. Equation: 2Na(s) + Cl2(g) → 2NaCl(s). The compound formed has properties very different from sodium and chlorine.

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They combine chemically to form iron sulphide, a black compound. Equation: Fe(s) + S(s) → FeS(s). The product is not attracted by a magnet and does not dissolve in carbon disulphide.

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Sample A is a mixture of iron filings and sulphur before heating. Iron is attracted by a magnet, and sulphur dissolves in carbon disulphide. The components keep their own properties.

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Sample B is the black compound iron sulphide formed after heating iron and sulphur. It is not attracted by a magnet and does not dissolve in carbon disulphide.