Chem Unit 3 Historical Figures

study study pookie

Democritus

Creator of atomic theory of the universe, came up with the term “Atom” meaning “invisible” (1st philosopher (oldest))

Aristotle

Believed matter was made up of ‘elements’ such as wind, fire, water, and earth (2nd philosopher)

John Dalton

Came up with their own version of “atomic theory” and its rules (3rd Physicist/chemist) thought atom was just sphere of neutral charge

Dalton’s atomic theory proven wrong

2. Atoms of a given element are identical in size, mass, and other properties

3. Atoms can NOT be subdivided, created, or destroyed

Dalton’s atomic theory proven correct

1. All matter is composed of very small particles called “atoms”

4. Atoms of diff elements can combine in a hole bunch of ratios

5. in chem reactions, atoms are combined, separated, or re-arranged

JJ Thomson

Discoverer of the electron using cathode ray experiment (4th physicist) theory that atom was made up of mostly positively charged atoms sprinkled with negative electrons (choco cookie)

Cathode ray experiment

tube with stream of particles moving through tube and by placing positively and negatively charged plates against the tube (found that the negative plate deflected the particles so JJ knew that they must have a negative charge (electrons))

Ernest Rutherford

Discovered protons and the Nucleus by conducting Gold foil experiment (dense positively charged center) (5th physicist)

Gold Foil Experiment

Shot positively charged particles at gold atoms (if the atom looked like choco cookie then that particles should just pass on through because no dense area of pos atoms), some of the particles went through and some bounced off of the gold (confirmed dense positive charge), most of the atoms went through the gold showing that atom is mostly full of empty space.

Niels Bhor

Found that electrons are in energy levels in atom, creator of the solar system model (6th physicist)

Erwin Schrodinger

Created Cloud model, believed that electrons are waves not particles, (7th Theoretical physicist)

Cloud Model

Shows the probability of where to find electrons (orbitals 90%)

James Chadwick

Found the neutron using Polonium Geiger Counter Experiment (8th Theoretical physicist)

Polonium Geiger Counter Experiment

Alpha particles released through two walls to see what atoms would pass through each wall

Werner Heisenberg

found that an electron is indeed a particle, but described as a wave. Quantum Theory (9th Theoretical physicist)