Chemical Reactions

How important are chemical reactions?

Long ago, people discovered that:

  • substances can react to make new substances
  • these reactions can be controlled

The science of chemistry began when people began experimenting with chemical reactions in a systematic way and organizing their results logically.

As chemistry developed, one of the things scientists learned was that living things exist only as a result of chemical reactions – and this includes you.

Every living thing is a remarkably well-organized, self-managing chemistry set.


Are we just remarkably sophisticated chemistry sets?

Furthermore, our high tech society would be impossible without our ability to control chemical reactions – the screen you’re viewing right now is just one example of a device that would be impossible to make.

So, on a one to ten scale of scientific importance, chemical reactions rate ten.

People started reacting chemicals a long time ago

Our ancient ancestors learned:

  • How to harness and control the reaction between oxygen and wood to make fire.
  • How to release metals from their ores. This enabled them to make efficient plows, axes, hammers and chisels.
  • How to disinfect/fumigate rooms and buildings with the gas released by burning sulfur (sulfur dioxide).
  • How to convert limestone into what we now call calcium oxide. Complex, large-scale construction projects such as ancient Rome’s Colosseum became possible, because calcium oxide is the basis of cement and concrete.
The Colosseum , Rome

The Colosseum was built using calcium oxide cement. This building is almost 2000 years old. Image by Paul Zangaro

Not all uses were peaceful

Our ancestors used new materials, such as iron and steel, to wage war. They discovered explosive chemical reactions and made gunpowder by mixing potassium nitrate, carbon, and sulfur.

We’re still making new discoveries

Although we know a lot more about chemistry than our ancestors did, we continue to study chemical reactions, because this leads to improvements in our technology and our health.

Mobile technology depends on chemistry, from the plastics of the structure to the high energy density lithium batteries that provide power.

Mobile technology depends on discoveries made by chemists – from plastics to lithium-ion batteries.

The sheer excitement of making new discoveries also drives chemists to continue investigating reactions.


  • Lithium reactions power our phones, tablet computers and cameras.
  • Biochemical and electrochemical reactions allow our brains to think and store memories.
  • Reactions to produce new antibiotics are needed, because some bacteria are becoming resistant to the antibiotics we’re using today.

On the next page:

Contents of Page 2

  • Reactants and products in reactions
  • How we can tell there’s been a chemical reaction
  • Signs of a chemical reaction
  • Test yourself with Questions with Answers