Write the postulates of Dalton’s atomic theory.

Dalton said matter has tiny indivisible atoms, atoms of an element are identical, atoms combine in simple whole-number ratios to form compounds, and chemical reactions rearrange atoms without creating or destroying them.

Detailed list of postulates

• All matter is made of atoms. Atoms are very small particles.
• Indivisible and indestructible (historic view): Atoms cannot be created or destroyed in chemical changes.
• Atoms of an element are identical. Same mass and properties for one element.
• Atoms of different elements differ. Different masses and properties.
• Law of definite proportions: Compounds form when atoms combine in simple whole-number ratios.
• Law of multiple proportions: If two elements form more than one compound, the masses of one that combine with a fixed mass of the other are in small whole-number ratios.
• Chemical reactions are atom rearrangements. Atoms are neither created nor destroyed.

Modern notes

• Atoms are divisible into subatomic particles, but Dalton’s ideas still frame basic chemistry.
• Isotopes show atoms of the same element can have different masses.