Molecule
From Wikipedia, a free encyclopedia written in simple English for easy reading.
A molecule is the smallest amount of a chemical substance that can exist. If a molecule were split into smaller pieces, it would be a different substance.
Molecules are made up of atoms that are stuck together in a particular shape. Not all combinations of atoms are possible; atoms like certain shapes, but not others. For example, oxygen atoms always have two bonds with other atoms, carbon atoms always have four bonds with other atoms, and nitrogen atoms always have three bonds with other atoms.
In gases like air, the molecules are just flying around. In liquids like water, the molecules are stuck together but they can still move. In solids like sugar, the molecules can only vibrate.
With a molecular formula, you can write down the numbers of all atoms in a molecule. For example, the molecular formula of sugar is C6H12O6. That means that one molecule of sugar is made up of six carbon atoms, twelve hydrogen atoms and six oxygen atoms.