Is the Atom Fundamental?

Around 1900, people thought of atoms as tiny balls.

• However, the fact that atoms could be categorized in terms of their similar chemical properties (as in a periodic table) suggested that atoms are not fundamental.

• Moreover experiments which "looked" into an atom using particle probes indicated that atoms had structure and were not just permeable balls.

• These experiments helped scientists determine that atoms had a positive, dense nucleus and a cloud of electrons (e).