Nature of Matter: Elements, Compounds, and Mixtures
Elements
Learn what elements are, the simplest pure substances.
Hydrogen and oxygen, the two gases that came out of water, are pure substances called elements.
An element is a substance that can't be broken down into anything simpler. Elements are the building blocks of all matter. Gold, silver, sulfur and carbon are elements too.
Each element is made of identical particles called atoms, and the atoms of one element are different from those of every other element. Iron is made of iron atoms, gold of gold atoms.
The atoms of most elements can't exist on their own. Two or more atoms of the same element join to make a stable particle called a molecule. Two hydrogen atoms make one hydrogen molecule; two oxygen atoms make one oxygen molecule.
Elements fall into groups:
| Group | Examples |
|---|---|
| metals | gold, silver, magnesium, iron, aluminium |
| non-metals | carbon, sulfur, hydrogen, oxygen |
| metalloids (in between) | silicon, boron |
You'll learn more about metalloids in higher classes.
118 elements are known today, and most of them are solids. Eleven are gases at room temperature, and all eleven are non-metals, including oxygen, helium and nitrogen.
Only two elements are liquid at room temperature: mercury (a metal) and bromine (a non-metal). Gallium and caesium are solids, but they melt at only about 30 °C (303 K), just above room temperature.
Practise this lesson
Questions that get harder as you improve, a Tutor that helps without giving the answer away, and progress you can see. Free for every learner.
No account, no email address. Opens the real product.