Scientists

Question 1

Democritus

Answer 1

Atomism (Atoms are indivisible)

Question 2

Atomism

Answer 2

Democritus - The idea that matter is made out of atoms - Atoms are indivisible

Question 3

Proust

Answer 3

Law of Definite Proportions - Any given compound always contains the same ratios of elements (disproved the “clay” model)

Question 4

Dalton

Answer 4

Billiard Ball + Law of Multiple Proportions + Brought back Atomism

Question 5

Law of multiple Proportions

Answer 5

Dalton - Matter is in ratios of small whole numbers - Compound always has a certain composition

Question 6

Billiard Ball Model

Answer 6

Dalton - Atom is an indivisible sphere - Matter is composed of discrete particles that he envisioned tiny, indivisible spheres

Question 7

J. J. Thomson

Answer 7

Cathode Ray Tube Experiment (Discovering of Electrons) + Plum Pudding Model

Question 8

Cathode Ray Tube Experiment

Answer 8

J. J. Thomson - Glass tube with bulb at the end - Bulb is painted with phosphorescent paint - Cathode (negative) and Anode (positive) for power source - Set of charged metal plates inside the bulb. Proved that atoms contains negatively charged particles called electrons.

Question 9

Plum Pudding Model

Answer 9

J. J. Thomson - Electrons embedded in a positive “goo”

Question 10

Millikan

Answer 10

Oil Drop Experiment (Discovering the charge of an electron)

Question 11

Oil Drop Experiment

Answer 11

Millikan - Two electrically charged plates (Top is positive with a hole in the middle for droplets to go through and bottom is negative) - Oil Sprayer to put oil particles in the experiment - x-rays shoot in bottom to knock electrons off of air particles - Makes oil droplets negatively charged in result - Microscope for observer to see particles levitate. The electrical force cancels out gravity and this experiment allows Millikan to calculate the amount of charge of an electron.

Question 12

Rutherford

Answer 12

Gold Foil Experiment (Discovering the neutron) + The Nuclear Model

Question 13

Gold Foil Experiment

Answer 13

Rutherford - A source of alpha particles shoots a stream of particles at the thin piece of gold foil - The Gold foil is surrounded by a fluorescent screen that glows whenever an alpha particles strikes it to visually show the results of the experiment. Results shows that rarely, some alpha particles bounced off of the gold foil, proving that atoms are mostly empty space, with positive charge concentrated in a nucleus.

Question 14

The Nuclear Model

Answer 14

Rutherford - Small, dense area of positive charge

Question 15

Bohr

Answer 15

The Planetary Model (Electron roads like the planets’ orbit lines) + the emission spectra of hydrogen based on quantized energy levels

Question 16

The Planetary Model

Answer 16

Bohr - Electrons orbit the nucleus at set energy levels - Electrons travel in distinctive circular orbits or shells

Question 17

Heisenberg

Answer 17

The Uncertainty Principle

Question 18

The Uncertainty Principle

Answer 18

Heisenberg - It is impossible to know the exact position of an electron or a photon - We can’t know the exact position and speed of an particle

Question 19

Schrodinger + Other Scientists

Answer 19

The Quantum Model (Cloud likely to find Electrons)

Question 20

The Quantum Model

Answer 20

Schrodinger + Other Scientists - Electrons exists in orbitals (Areas where they are likely to be found)