HISTORY OF THE HISTORY OF THE ATOMIC THEORYATOMIC THEORY

IMPORTANCE OF ATOMIC THEORY

MAJOR CONTRIBUTORSTHE “MODERN ATOMIC THEORY”

DEMOCRITUSDEMOCRITUS~400 B.C.STATED THE FIRST THEORY ABOUT ATOMS

ATOMOS - INDIVISIBLE

ARISTOTLEARISTOTLE~300 B.C.DISAGREED WITH D’S THEORY

MATTER IS MADE OF HYLE (ONE STUFF BUT FORM CHANGES BY TREATMENTS)

GIORDANO GIORDANO BRUNOBRUNO~1600

EXECUTED B/C OF HIS THEORIES ON ATOMS

ROBERT BOYLE ROBERT BOYLE & ISAAC & ISAAC NEWTONNEWTON~1600 A.D. (WORKED

INDEPENDENTLY)DISCUSSED THE POSSIBILITY OF ATOMS EXISTING

PROGRESS IMPEDED BY THE CHURCH

ANTOINE ANTOINE LAVOISIERLAVOISIER

~1700 A.D.KNOWN FOR HIS EXPERIMENTATION SKILLS

STATED THE LAW OF CONSERVATION OF MATTER

ANTOINE ANTOINE LAVOISIERLAVOISIER

STATED THE LAW OF CONSERVATION OF MATTER

(HINTS AT THE REARRANGEMENT OF MATTER IN REACTIONS)

JOSEPH PROUSTJOSEPH PROUST~1700 A.D.STATED THE LAW OF DEFINITE PROPORTIONS

(HINTS AT THE “LEGO”NESS OF MATTER)

JOHN DALTONJOHN DALTON~1800 A.D.DID “LIBRARY” RESEARCH

STATED DALTON’S ATOMIC THEORY

MODERN ATOMIC MODERN ATOMIC THEORYTHEORY

DIFFERENCES BETWEEN DALTON’S AND MODERN:ATOMS CAN BE DIVIDEDATOMS OF SAME ELEMENT CAN HAVE DIFF MASSES

““WONDERINGS”WONDERINGS”

Q: “What is matter made of?”A: AtomsQ: “What are ATOMS made of?”

A: “hmmmmm… good question!”

HISTORY OF HISTORY OF ATOMIC ATOMIC STRUCTURESTRUCTURE

THOMSONTHOMSON1897CATHODE RAYS = e-

DETERMINED THE CHARGE TO MASS RATIO

DEVELOPED THE “PLUM PUDDING MODEL” OF ATOM

RUTHERFORDRUTHERFORD“EARLY 1900’S”PROPERTIES OF RADIOACTIVITY

= He+2

= e-

= LIGHT

RUTHERFORD RUTHERFORD (AGAIN)(AGAIN)

1910-1911GOLD FOIL EXPERIMENTNUCLEAR MODEL

MILLIKANMILLIKANEarly 1910’SOIL DROP EXPERIMENT DETERMINED THE CHARGE OF AN ELECTRON

THEREFORE, WE KNOW THE MASS

RUTHERFORD RUTHERFORD (YET AGAIN)(YET AGAIN)

1919PROTONS

CHADWICKCHADWICK1932NEUTRONS