Elements, Compounds & Mixtures (Cambridge (CIE) O Level Chemistry): Revision Note

Elements, Compounds & Mixtures

Elements, compounds and mixtures

• All substances can be classified into one of these three types

Element

• A substance made of atoms that all contain the same number of protons and cannot be split into anything simpler

• There are 118 elements found in the Periodic Table

Compound

• A pure substance made up of two or more elements chemically combined

• There is an unlimited number of compounds

• Compounds cannot be separated into their elements by physical means

• E.g. copper(II) sulfate (CuSO₄), calcium carbonate (CaCO₃), carbon dioxide (CO₂)

Mixture

• A combination of two or more substances (elements and/or compounds) that are not chemically combined

• Mixtures can be separated by physical methods such as filtration or evaporation

• E.g. sand and water, oil and water, sulfur powder and iron filings 

Particle diagram showing elements, compounds and mixtures