Dalton pictured the atom as a tiny, solid, indestructible sphere.

Dalton developed an atomic theory:

- Elements are made of tiny particles called atoms.

- Atoms cannot be created, divided into smaller particles, nor destroyed in the chemical process; a chemical reaction simply changes the way atoms are grouped together.

- All atoms of a given element are identical.

- The atoms of a given element are different than those of any other element and can be distinguised from eachother by their atomic weights.

- Atoms of one element can combine with atoms of other elements to form chemical compounds.