Evolution of The Atomic Theory

He concluded that atoms have protons located in the nucleus.

He was the first to identify subatomic particles.

He concluded that the negative charges came from within the atom.

He was the first to identify the nucleus of the atom.

Early 1800s, the English Chemist

Atom Charge

All elements are composed of atoms. Atoms are indivisible and indestructible particles.

He concluded the negative charges came from within the atom.

Stated electrons move in definite orbits around the nucleus, much like planets circle the sun.

Concluded the orbits are actually energy levels, located at certain distances from the nucleus

He named the smallest piece of matter “atomos,” meaning “not to be cut.”

Electron Charge...

He stated that matter could not be divided forever and called the smallest piece-atomos.

He found that the neutron does not have a charge (neutral).

He stated atoms of different elements are different.

Matter could not be divided into small pieces forever

Gold Foil Test.

He concluded that atoms were mostly “open space.”

He was the first to call the negatively charged particles electrons.

Neutron Charge...

His theory became one of the foundations of modern chemistry.

He stated atoms were infinite in number, always moving and capable of joining together.

He concluded that small particles do exist in atoms.

Plum Pudding Model

He stated atoms of the same element are exactly alike.

Proton Charge...

Atoms were small, hard particles that were all made of the same material/were different sizes

He concluded that the atom was divisible which was contradictory to Democritus and Dalton.

He concluded that there were positively charges particles within the atom.