Atomic Theory

Discovered that atoms have a positive charge in the core and negative charges outside the core. Atoms are mostly made of space.

Ernest Rutherford

Discovered that atoms can be split into smaller particles (protons and electrons).

J.J Thomson

An atom is a ball of positively charged material with negatively charged particles floating around inside.

Proposed the Law of Conservation of Matter Created the metric system

Matter cannot be created or destroyed. It can only be converted into other matter.

Atoms of the same element are exactly alike. Atoms of different elements are different. Atoms can join with other atoms to make new substances.

Electrons travel around the nucleus of an atom in definite paths. Electrons can jump from one energy level (path) to another.

The exact location of an electron cannot be found. Electrons travel in electron clouds which represent where the electron is most likely to be found.

Discovered the existence of neutrons. He found that the atomic mass of most elements is double the number of protons for one atom of that element.

Similar to a model of the solar system. The nucleus (with protons) is in the center. Electrons orbit the nucleus in different levels.

First level (K) = 2 Second level (L) = 8 Third level (M) = 8 Fourth level (N) = 18 Fifth level (O) = 18 Sixth level (P) = 32 Seventh level (Q) = 32

The number of Protons

Atomic Mass - Atomic Number = # of Neutrons

Protons = Electrons

A beam of positively charged particles was aimed at a piece of gold foil. Most of the light passed through the foil in a straight line. Many particles bounced off the foil in different directions.

Positively charged particles

Negatively charged particles

Neutral charged particles

The nucleus