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Science

Properties and reactions of elements

Hazard symbols and safety

Some chemicals can harm us if they are not handled carefully. Hazard symbols are used to identify the danger posed by each chemical and what care should be taken.

Hazard symbols and what they mean

SymbolMeaning
liquid dripping on hands in black on yellow background

Corrosive

Concentrated solutions of strong acids and strong alkalis are labelled with the 'corrosive' symbol. Anyone using a corrosive substance should wear gloves and eye protection, such as goggles or a face shield.

black x on yellow background with a small 'i' in the bottom right corner

Irritant

Dilute solutions of acids and alkalis are labelled with the 'irritant' symbol. Anyone using an irritant substance should wear eye protection such as goggles, and they should take care to wash any spills off their skin immediately.

black skull and crossbones on yellow background

Toxic

Very poisonous chemicals are labelled with the 'toxic' symbol. Anyone who uses a toxic chemical needs to take great care. They should wear gloves and eye protection, and they may wear a mask over their mouth and nose, or handle the chemical in a fume cupboard.

black x on yellow background with a small 'h' in the bottom right corner

Harmful

Less poisonous chemicals are labelled with the 'harmful' symbol. Anyone using a harmful substance should wear eye protection such as goggles, and they should take care to wash any spills off their skin immediately.

a black fire on yellow background

Highly flammable

Chemicals that ignite very easily are labelled with the 'highly flammable' symbol. In addition to the normal precautions of wearing eye protection, anyone using a highly flammable substance should take care to keep it away from flames and sparks, and also from oxidising substances.

an 'O' with a fire on top in black, on a yellow background

Oxidising

Oxidising substances do not burn themselves, but they provide oxygen for flammable substances to burn. They are labelled with the 'oxidising' symbol. In addition to the normal precautions of wearing eye protection, anyone using an oxidising substance should take care to keep it away from flammable substances, including clothing.

An illustration of an explosion (Crown Copyright; Health and Safety Executive)

Explosive

Explosive substances have enough stored energy in them that if treated incorrectly they may explode. These materials are labelled with the 'explosive' hazard symbol. Explosive substances must be handled very carefully. It is illegal to carry out unauthorised experiments with explosive chemicals.

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