John Dalton

Indivisible atoms

All matter is made of indivisible atoms that cannot be created or destroyed.

Identical atoms of the same element

Atoms of the same element are identical in size, mass, and other properties.

Different atoms of different elements

Atoms of different elements differ in size, mass, and other properties.

Compound formation

Atoms of different elements can combine in simple whole-number ratios to form chemical compounds.

Chemical reactions

Chemical reactions are the result of atoms being combined, separated, or rearranged.

Dalton's atomic theory

The first comprehensive explanation of matter regarding atoms and their properties.

Postulates of Dalton's atomic theory

Five statements outlining the characteristics of atoms and their behavior.

Simple whole-number ratios

The way atoms of different elements combine to form compounds.

Matter

Anything that has mass and takes up space, composed of atoms.

Atomic properties

Characteristics like size, mass, and behavior that differentiate atoms.