CONCEPT OF ATOMS AND MATTER

MATTER

ANYTHING that has MASS and occupies SPACE

ATOM

SMALLEST UNIT of MATTER that retains the PROPERTIES of an ELEMENT

ATOMISM (DEMOCRITUS & LEUCIPPUS, 400 BC)

MATTER is made of ATOMS and VOID; ATOMS differ in SHAPE and SIZE and move and COLLIDE in the VOID

NON-ATOMISM (ARISTOTLE, 400 BC)

MATTER is CONTINUOUS and composed of ELEMENTS and ESSENTIAL QUALITIES like HOT, DRY, WET, and COLD

EMPEDOCLES (450 BC)

PROPOSED FOUR ELEMENTS of matter: EARTH, AIR, FIRE, WATER

PLATO

Elaborated EMPEDOCLES' theory; said ELEMENTS are made of tiny, indivisible GEOMETRIC SHAPES (TRIANGLES) called PLATONIC SOLIDS

Tetrahedron - FIRE - 4 F - 24 T
Cube - EARTH - 6 F - 24 T
Octahedron - AIR - 8 F - 48 T
Icosahedron - WATER - 20 F - 120 T

ARISTOTLE

Added a FIFTH ELEMENT called AETHER/ETHER representing SPACE; believed ELEMENTS combined to form QUALITIES

ALCHEMY

From GREEK khemeia and ARABIC alkimia, meaning the ART OF TRANSFORMATION

CHEMISTRY

SCIENTIFIC STUDY of PROPERTIES, COMPOSITION, and STRUCTURE of MATTER

Civilizations

MESOPOTAMIAN CHEMISTRY - Used GOLD and COPPER
EGYPTIAN CHEMISTRY - Used DYES, GLASS, and BRONZE
CHINESE CHEMISTRY - Known for METALWORK, CERAMICS, and MEDICINE
INDIAN CHEMISTRY - Known for RASAYANA, IRON, STEEL, and MEDICINE
ARAB CHEMISTRY - Specialized in PURIFICATION of METALS
FIRST CHEMICAL REACTION - FIRE

Scientific Contribution

Developed DISTILLATION, EVAPORATION, and other PROCESSES; discovered PHOSPHORUS, SULFUR, and POTASH

Unscientific Contribution

Used MAGIC, SPELLS, ASTROLOGY; focused on IMMORTALITY and SPIRITUAL TRANSFORMATION

JOHN DALTON (1808)

Proposed the ATOMIC THEORY and the LAW OF MULTIPLE PROPORTIONS

DMITRI MENDELEEV (1869)

Created the PERIODIC TABLE arranged by ATOMIC MASS

DALTON'S MODEL

SOLID SPHERE or BILLIARD BALL MODEL

1803

JOSEPH JOHN THOMSON

discovered the electron
CATHODE RAY EXPERIMENT
-CATHODE RAYS are NEGATIVELY CHARGED, have very LOW MASS, and are SUBATOMIC PARTICLES

1/1837 Lighter than hydrogen

PLUM PUDDING MODEL

J.J. THOMSON's model of the ATOM where ELECTRONS are scattered in a POSITIVE "pudding"

1904

ROBERT MILLIKAN

Used the OIL DROP EXPERIMENT to determine the CHARGE of an ELECTRON = -1.6022 × 10⁻¹⁹ C

ERNEST RUTHERFORD

Discovered the PROTON using the GOLD FOIL EXPERIMENT

NUCLEAR MODEL

RUTHERFORD'S model placing PROTONS in a small, dense NUCLEUS with ELECTRONS orbiting

1911

PLANETARY MODEL

NEILS BOHR'S model with ELECTRONS in FIXED ENERGY LEVELS or SHELLS

1913

K -2
L -4
M -6
N - 8

QUANTUM MECHANICAL MODEL

ERWIN SCHRODINGER'S model with ELECTRON CLOUDS and the UNCERTAINTY PRINCIPLE

1926

JAMES CHADWICK (1932)

DISCOVERED the NEUTRON

With Gold Foil Experiment but instead of gold he used BERYLLIUM

SUBATOMIC PARTICLES

• ELECTRON → NEGATIVE charge, OUTSIDE the nucleus• PROTON → POSITIVE charge, INSIDE the nucleus• NEUTRON → NO charge, INSIDE the nucleus

CHARGE AND MASS

• ELECTRON: -1, 9.1094 x 10⁻²⁸ g
• PROTON: +1, 1.6726 x 10⁻²⁴ g
• NEUTRON: 0, 1.6740 x 10⁻²⁴ g

Charge - Elec (-1.6022 x 10 ^-19)