---
categories:
  - Electronics
tags: [physics]
---

# Matter and atoms

- Matter is any substance that has weight. It can take the form of a liquid, a solid, or a gas.
- Matter comprises **elements** and **compounds**

## Atoms and molecules

An element is any matter that cannot be divided further by chemical means. Elements are made up of atoms. Elements can join together to form compounds. A molecule is a type of compound where the atoms of two types of elements have joined together to form a more complex type of matter. The parts of a molecule, in contrast to elements, can be separated by chemical means. For example Sodium and Chlorine are two elements that can join to form Sodium Chloride. We call this **chemical bonding**. We can use chemistry to separate the Sodium and Chlorine atoms in the molecule to return to two separate elements.

Compounds can be confusing. In general a compound is any matter that contains more than one kind of element. By this definition a molecule is always a compound. However not every compound is a molecule as we can have complex compounds that contain more than one type of molecule. For example water is hydrogen and oxygen forming a molecule. It contains more than one element therefore it is a compound. But imagine if we had water and carbon combined. This would still be a compound but not a molecule since it would contain a molecule and a carbon element.

## Atomic particles

There are three particles comprising atoms: protons, neutrons and electrons.

Protons and neutrons comprise the nucleous of the atom. A proton is positively charged. A neutron has no charge.

Electrons orbit around the nucleous in concentric rings. Electrons are negatively. Because of this protons and electrons attract each other.