Inventors of the Atoms

Democritus and Dalton

discovered that matter is composed of tiny indivisible particles called atoms (billiard ball)

Atom

smallest part of an element that retains the chemical properties of that element

Lavoisier and Dalton

discovered that the Law of Conversation of matter states that matter is neither created nor destroyed

Father of Chemistry

Lavoisier is known as...

Proust and Dalton

discovered the Law of Definite Properties (Constant Composition) states that compounds always have the same elements in the same proportion by mass

Ben Franklin

first to suggest the structure of the atom was related to electricity. He found that there were two types of charge

repel

negative and negative

attract

negative and positive

repel

positive and positive

Cathode Ray Tube

an evacuated glass tube where a beam of electrons flows from the cathode (negative electrode) to the anode (positive electrode)

J.J. Thomson

discovered that a cathode ray is made of electrons, they have mass and are negatively charged particles

Henri Becquerel

discovered accidentally radioactivity using pitchblende, a uranium ore (a rock that has metal in it)

Radioactivity

the spontaneous emission of matter and energy from a sample. it exposed the film in Becquerel's drawer and left an image

Marie and Pierre Curie

shared the Nobel Prize in chemistry with Becquerel. They discovered 2 new radioactive elements, radium and polonium

Ernest Rutherford

found 3 types of natural radiation or radioactive decay

a (alpha)

large +2 charge

b (beta)

small -1 charge

y (gamma)

neutral no charge

Ernest Rutherford

Alpha Scattering or Gold Foil Experiment discovered a small, central positive nucleus, and that most of the atom is empty space

J.J. Thomson

thought the atom looked like "plum pudding" with negative charges distributed throughout

Ernest Rutherford

small dense positive nucleus (protons) with electrons outside

Neils Bohr

thought the atom was like the solar system (planetary model). this was inaccurate and too simplistic

James Chadwick

determined that the atom also contained a neutron (proton and electron fused together)

Wave(Electron Cloud) Model

using Quantum Mechanics, the electron can be found in a probability region

John Moseley

determined that each atom has its own atomic number (number of protons)