What is the difference between an element and a compound?

The key difference between elements and compounds lies in their composition:

• Elements: Elements are pure substances made up of only one type of atom. They cannot be broken down into simpler substances by chemical means. Examples include oxygen (O), gold (Au), and hydrogen (H). Each element is defined by the number of protons in its atoms (its atomic number).

• Compounds: Compounds are pure substances made up of two or more different types of atoms chemically bonded together in a fixed ratio. They can be broken down into simpler substances (elements) by chemical means. Examples include water (H₂O), salt (NaCl), and carbon dioxide (CO₂). The properties of a compound are distinctly different from the properties of the elements that make it up.

Here's a table summarizing the key differences:

Feature	Element	Compound
Composition	One type of atom	Two or more types of atoms
Bonding	No chemical bonds between different atoms	Chemical bonds between different atoms
Breakdown	Cannot be broken down chemically	Can be broken down chemically into elements
Properties	Unique properties	Properties different from constituent elements

In essence, elements are the fundamental building blocks of matter, while compounds are substances formed by combining these building blocks in specific ways.