Chemistry — 6-topic bundle

You encounter matter every second of every day. From the air you breathe to the phone in your hand, it's all matter.

Photo by Ann H on Pexels

When we talk about pure substances, we mean materials that have a uniform and definite composition. This means every bit of that substance is exactly the same, with no other materials mixed in. Pure substances are divided into two main categories: elements and compounds.

Here's the key distinction:
* All compounds are molecules (because they have atoms bonded together).
* However, not all molecules are compounds (e.g., O$_2$ is a molecule but an element, not a compound).

In chemistry, pure substances are materials made of only one type of matter, with a fixed chemical composition and distinct properties. Think of pure gold or pure water.

There are two main types of pure substances: elements and compounds. For now, we'll focus on elements.

When two or more substances combine but don't chemically react to form new substances, you've got a mixture. The key idea is that each substance keeps its original properties.

Photo by Ivan S on Pexels

When we talk about chemistry, we're talking about atoms and how they combine. Chemical formulas and particle diagrams are two essential ways to describe these combinations.

Photo by Artem Podrez on Pexels