Since everything around you is made of matter, everything you see is chemical. In this lesson, you will learn what a chemical is, how to classify chemicals based on how they are used and how dangerous or hazardous they are, and how to stay safe when using chemicals, especially dangerous or hazardous ones.

Meaning of chemicals

A chemical is a substance that is made or used in a chemical process and has a specific molecular structure. Everything you see is made of matter, so everything you see is chemical. Remember that matter is anything that has weight and takes up space. The air you breathe is a mixture of gases. The water you drink is a chemical compound made of hydrogen and oxygen (H2O). The common salt you use in cooking is made of sodium and chlorine (NaCI). Can you think of anything that doesn’t have a matter in it?

Classes of chemicals

Chemicals can be put into groups based on how they are used and how hazardous they are.

Classification of chemicals based on their uses

Pharmaceuticals and cosmetics

These are chemicals used to treat diseases.   They are also referred to as drugs. Aspirin, paracetamol, morphine, and penicillin are all examples of medicines.

On the other hand, cosmetics are made of chemicals that are used to make the body look better. Examples include lipsticks, fragrances, deodorants, hairsprays, eyeliners, etc. Makeups and body care products are other names for cosmetics.

Nuclear chemicals

These are chemicals that are created or used during nuclear reactions. Nuclear chemicals like uranium and plutonium are very likely to cause cancer, and being around them can be bad for your health.


The word “agrochemical” is made up of two words: “agriculture” and “chemical.” Agrochemicals are chemicals that farmers use to make farming easier. They include fertilisers, insecticides, fungicides, herbicides, etc.

Industrial chemicals

These are chemicals that are usually used in the chemical industry. Many useful things are made from these chemicals. Polyethene and polyvinyl chloride are examples of industrial chemicals. They are used to make plastics and polymers.

Laboratory chemicals

These are chemicals that are used often in labs. They include chemicals like sodium hydroxide (NaCI), potassium nitrate (KNO3), and hydrogen chloride (HCI).

Classification of chemicals based on their hazardous nature

Highly hazardous and toxic chemicals

These are chemicals that are dangerous and can kill if they get into the environment. Even the smallest amount of exposure to these chemicals can kill you. Examples include Arsenic trioxide

  • Chlorine
  • Hydrogen cyanide
  • Nitrous oxide
  • Phosgene
  • Potassium cyanide (analytical reagent and purified)
  • Sodium arsenate (analytical reagent)
  • Sodium cyanide (analytical reagent)

Moderately hazardous and toxic chemicals

These chemicals are dangerous to your health, but they won’t kill you. Examples are

  • Tobacco.
  • Asbestos dust.
  • Cocaine
  • Heroin
  • ecstasy.
  • Petrol
  • cooking gas
  • Pesticides
  • Insecticides

Non-hazardous and non-toxic chemicals

These substances are neither dangerous nor poisonous. When exposed to them, they do little or no harm. Agar, chitin, folic acid, and calcium sulphate are all examples.

  • Baking soda.
  • Borax 
  • Lemon
  • Washing soda
  • Isopropyl alcohol
  • Sodium
  • Salt
  • sodium alginate
  • Amylase
  • alcohol dehydrogenates
  • calcium carbonate
  • egg alum
  • folic acid, etc.

Safety measures when using chemicals

  • When using chemicals, especially dangerous ones, the following safety measures must be taken:
  • Follow the safety guidelines for storing and handling the chemicals. Read and follow the safety signs and instructions on the chemical packages. 
  • Follow the safety guidelines for storing and handling the chemicals. Read and follow the safety signs and instructions on the chemical packages. 
  • Before going into the lab, read all the instructions carefully. 
  • Don’t mess around in the lab. Horseplay, pranks and practical jokes are dangerous and not allowed.
  • Always work in a place with good ventilation.
  • Keep the property in good shape. 
  • Work areas should always be clean and organised.
  • Always be aware and move carefully in the laboratory.
  • Tell the teacher right away if you see anything that makes you feel unsafe.
  • Do the right thing with all chemical waste.
  • Don’t put chemicals down the same drain.
  • Sinks are only for putting water in.
  • Find out how to get rid of chemicals and solutions from your teacher.
  • Before using something, you should carefully read the labels and instructions.
  • Set up the equipment and use it the way your teacher tells you to.
  • When using chemicals or lab equipment, keep your hands away from your face, eyes, mouth, and body.
  • After each experiment, wash your hands with soap and water.
  • Experiments must always be watched by a person. 
  • Don’t walk around the room, bother other students, scare other students, or get in the way of what other students are doing in the lab.
  • Know where all safety equipment, like first aid kits and fire extinguishers, is and how to use it. 
  • Find out where the fire alarm is and where the exits are.
  • Know what to do if there is a fire drill during a lab period. 
  • Know what to do if there is a fire drill during a lab period. 
  • Students should wear safety goggles whenever chemicals, heat, or glassware are used.
  • Dress appropriately for a lab activity. Long hair, jewellery that dangles, and loose or baggy clothes can be dangerous in the lab. Long hair must be tied back, and jewellery that dangles and clothes that are too big must be fastened. Shoes must cover the foot completely. 
  • On lab days, you cannot wear sandals.
  • During lab experiments, you should wear a lab coat or smock.
  • Pay attention to and follow the warnings and instructions on chemical packages.
  • All of the chemicals in the lab should be treated as dangerous. Don’t use your fingers to touch chemicals. Use a tweezer every time.
  • Keep at least a foot away from the specimen when making an observation. 
  • Do not smell or taste chemicals.
  • Before taking anything out of a chemical bottle, check the label twice.
  • Don’t take more of the chemical than you need.
  • Don’t put chemicals back in their original containers after you’ve used them.
  • Don’t take any chemicals or other materials out of the lab.

Chemical Storage and Labeling

Differentiate between chemicals that are dangerous and those that are not.

  • Use the chemical’s physical state (dry, liquid, or gas) to figure out where to store chemical
  • Make a chemical list to figure out how dangerous your chemicals are.
  • Labelling dangerous chemicals and waste correctly is very important to reduce exposure, avoid accidents, and avoid paying more to get rid of them.
  • Label all chemicals with their full English name (no chemical formations or abbreviations), the date, any dangers they pose, and the name of the person responsible. 
  • Labelling chemicals correctly is an important part of planning for and preventing emergencies.
  • In the event of an accident, such as a fire or a person being exposed to a chemical, it can be very important to know what the physical and health dangers of the chemical are. This can help keep health problems and property damage to a minimum. 
  • Chemicals that aren’t properly labelled or can’t be identified can end up as “unknown” chemical waste.
  • Trying to figure out what is in a chemical that is “unknown” is a long and expensive process. It also poses unique concerns and risks for people who deal with chemical waste and for the environment.
  • Please take care not to make chemicals that are “unknown” in your lab.

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