Atoms and Molecules
The two smallest units of matter are atoms and molecules. To understand what a molecule is you first need to know about atoms.
An atom is the most basic element of matter. It is made up of three basic parts: The central nucleus that consists of positively charged protons and neutrally charged protons. Circling this nucleus are negatively charged electrons. If there are more electrons, the atom has a negative charge. An excess of proton gives it a positive charge. An atom seeks to become stable by having the same number of electrons and protons. To achieve this, sometimes the atom needs to find another atom with an opposite charge.
When two or more of these atoms stick together they create a molecule. The molecule will have the same number of protons and electrons, meaning that it has no electrical charge. A common example of this is salt. A molecule of salt is composed of two atoms, sodium (Na–) and chloride (Cl+). Sodium has a negative charge so it teams up with chloride which has a positive charge. The result is a molecule of table salt, NaCl, that has no charge and is stable.
A molecule doesn’t need to be made up different atoms. Oxygen, (O2) is an example of a molecule made up of two of the same atoms. There are also molecules made up of many atoms, such as DNA. The key to being a molecule, rather than a bunch of atoms is the bond formed between molecules and the stability. Molecular bonds are covalent (sharing electrons) and stable (not easily broken).
Molecular science is the study of how molecules interact and the properties of the structures they create. Many molecules can join together to make larger elements. A diamond, for example, is a crystal structure made up of carbon molecules.