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GCSE Combined Science · key term
Resistance to scratching or indentation.
Used by AQA and OCR
Specification 4.6.2.7 · Paper 3, Paper 4
Resistance to being scratched, indented or permanently deformed.
Revise: Properties of MetalsThe important connection is different-sized atoms → distorted layers → less easy sliding → greater hardness. Alloying changes the arrangement of the structure; stronger metallic bonds are not the explanation for this increase in hardness.
Chemistry, Combined Science
Explain alloy hardness using different-sized atoms, distorted layers and less easy sliding—not stronger bonds or layers that can never move.
Distinguish hardness, stiffness and strength: resistance to scratching, resistance to deformation and resistance to failure are different properties.
Hardness is not the same as strength or toughness. A material can resist scratching but still be brittle.
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Hardness means resistance to scratching or indentation. Brittleness means a material tends to crack or break rather than deform substantially. Glass can therefore be hard but brittle: it resists scratches yet can shatter when struck.
The resistance of a material to scratching or indentation.
