If you ask a chemist what a chemical is, they might say it’s a “reactive gas.” In other words, it’s a gas that can react with other things to make new molecules.
But if you asked a person what a chemical is, they would say it’s a “molecule.”
Here’s why. A molecule is made up of a nucleus (a nucleus is the central atom of a molecule) and a set of electrons. The electrons are shared between different atoms in a molecule, so molecules can vary in how many electrons they have.
Chemical reactions happen when molecules come in contact with each other. When two molecules come into contact, they can start to react. This is what happens when you put a gas like carbon dioxide and water together. The carbon dioxide will react with water, creating new molecules of carbon dioxide and water.
But there’s one important difference between chemical reactions and molecule interactions: chemical reactions happen in a lab, while molecule interactions happen in the real world.
So, when you ask a chemist what a chemical is, they might say it’s a “reactive gas,” but when you ask a person what a chemical is, they might say it’s a “molecule.”