Elements, compounds and mixtures
Three kinds of substance
- An element is made of only one type of atom (e.g. copper, oxygen) — it can't be broken down chemically.
- A compound is two or more elements chemically bonded in a fixed ratio (e.g. water).
- A mixture is substances just mixed, not bonded (e.g. air).
Practice
An element is a substance made of:
An element contains only one type of atom and cannot be broken down chemically.
Bonded or not
- In a compound the elements are bonded — only a chemical reaction can separate them, and the compound has new properties.
- In a mixture they are not bonded — the parts keep their properties and separate by physical methods.
Practice
The key difference between a compound and a mixture is that in a compound the elements are:
Compounds are bonded (separated only by chemical reaction); mixtures are not bonded (separated physically).
Practice
Classify each example.
Copper = one type of atom (element); water = bonded elements (compound); air = mixed gases (mixture).
You've got it
Key idea
- element = one type of atom; compound = elements bonded in a fixed ratio; mixture = not bonded
- a compound has new properties; a mixture's parts keep theirs
- mixtures separate physically; compounds need a chemical reaction