Democritus and Leucippus All matter is made of tiny indivisible solids. “Atomos” = Indivisible

Plato matter is made up of fire, water, and air. Their characteristics are due to the five solid shapes of the particles that make them.

Aristotle Atoms do not exist because matter is infinitely divisible. Differences in matter result from different combinations of fire, water, earth, and air.

Robert Boyle Proposed corpuscular theory. Tiny particles are the reason for differences in properties, but the particles can be divided.

Identified Hydrogen and oxygen Lavoisier Identified Hydrogen and oxygen

Determined the law of conservation of mass Lavoisier Determined the law of conservation of mass

Elements always combine in fixed proportions Proust Elements always combine in fixed proportions

Elements are made of atoms Dalton Elements are made of atoms

Atoms cannot be created, destroyed, or divided Dalton Atoms cannot be created, destroyed, or divided

Atoms combine in specific ratios to form compounds Dalton Atoms combine in specific ratios to form compounds

Atoms recombine during chemical reactions Dalton Atoms recombine during chemical reactions

Arranged elements by atomic weight and discovered patterns mendeleev Arranged elements by atomic weight and discovered patterns

Discovered the cathode ray phenomena faraday Discovered the cathode ray phenomena

Measured the mass of the cathode ray Jj thompson Measured the mass of the cathode ray

Discovered the electron Jj thompson Discovered the electron

Envisioned the atom as “plum pudding” Jj thompson Envisioned the atom as “plum pudding”

Rutherford + Geiger + Marsden Discovered the nucleus

Rutherford + Geiger + Marsden Discovered the atom is mostly space

Rutherford + Geiger + Marsden Conducted the gold foil experiment

Argued for particle theory of light Newton Argued for particle theory of light

huygens Light is a wave

Electrons exist in 4 energy levels bohr Electrons exist in 4 energy levels

Double slit interference Thomas young Double slit interference

Electromagnetic spectrum Based on wavelength: Rabbits mate in very unusual xpensive gardens

Quantum energy levels are like ladder rungs Planck’s constant Quantum energy levels are like ladder rungs

Quantum energy levels are like ladder rungs Planck’s constant Quantum energy levels are like ladder rungs

Massless packets of light photons Massless packets of light

Wavelength emitted by atoms… seen through a spectroscope Emission spectrum Wavelength emitted by atoms… seen through a spectroscope

Passing whit light through atoms Absorption spectrum Passing whit light through atoms

De broglie Matter can be wavelike

Matter is both like a wave and a particle Wave particle duality Matter is both like a wave and a particle

Heisenberg uncertainty principle Impossible to measure momentum and position at the same time

Electron clouds of probability Schrodinger model Electron clouds of probability