The Atomic Theory

Question 0

Democritus & Leocipidus

Answer 0

Proposed idea of atoms.
Matter is composed of small, indivisible pieces.
Particle Model of Matter

Question 1

Plato & Aristotle

Answer 1

Matter was infinitely divisible.

Continuous Model of Matter

Question 2

Pierre Gassendi

Answer 2

Translates Moorish texts on Atomic Theory & distributes these

Question 3

Robert Hook

Answer 3

Develops the Kinetic Theory of gases to explain the Gas Laws

Question 4

Joseph Proust

Answer 4

Chemically broke down pure substances (compounds) into the elements that composed them.
Found that every material had a fixed mass relationship b/n elements.
LAW of DEFINITE PROPORTIONS

Question 5

Antoine Lavoisseer

Answer 5

LAW of CONSERVATION OF MATTER

Matter is not created or destroyed (only changes form)

Question 6

John Dalton

Answer 6

LAW of MULTIPLE PROPORTIONS

-For substances made of the same elements there is a unique, fixed relationship between the elements for each

Question 7

Amadeo Avogadro

Answer 7

All gases of the same volume at the same conditions (pressure & temp) will have equal numbers of particles

Question 8

William Crookes

Answer 8

Invents the Cathode Ray Tube (1879)
Shows that the “beam of light” is actually a stream of – charged particles (attracted to + charged electric & magnetic fields)

Question 9

E. Goldstein

Answer 9

Used modified CRT; discovers “beam” of + charged particles (attracted to – charged electric & magnetic fields)

Question 10

J.J. Thomson

Answer 10

Works with CRT’s

Names – charged particles electrons

Question 11

Thomson’s Model of the Atom

Answer 11

Chocolate Chip Cook Model (Plum Pudding Model)
Since the atoms contain negative electrons & have no charge, there must be enough positive charge to cancel out the negative charge.

Question 12

Ernest Rutherford (worked with Neil Bohr & Hans Gelger)

Answer 12

Used radiation to “probe” atom.

Proposed the new model of an atom

Question 13

Dalton’s Assumptions of the Atomic Theory

Answer 13

1. Each element is composed of extremely small, indivisible, & (indestructible) particles called atoms.
2. All the atoms of an element are (identical). Atoms of different elements have different (masses).
3. Atoms of (different) elements can combine in simple-whole number ratios to form compounds.
4. Chemical reactions involve the rearrangement of atoms.
   a. Atoms aren’t changed into different types of atoms.
   b. Atoms are neither created or destroyed in chemical reactions.