ATOMIC PROGRESSION

DEMOCRITUS (460 BC -370 BC)

• Had a ballin' atomos theory
• His idea was rejected by most scholars of his time
• Aristotle specifically didn't like his theory
• Was pretty close to being right though
• So he got the last laugh I suppose.

ATOMOS THEORY

• Atoms are the smallest of something
• Means something that can't be cut any further
• Everything is composed of atoms
• Also credited to Democritus's mentor, Leucippus
• Atoms are invincible

ARISTOTLE (384 BC - 322 BC)

• Mentor to Alexander the Great
• Arguably the greatest philosopher of all time
• Created the foundation on which western society was built
• Unfortunately his hypotheses were not always correct

EARTH WIND FIRE WATER

• All things that exist are made from four base elements
• There is a fifth element known as aether, which composes the the stars and planets
• Earth things are solids, water was liquids, air was gas, and fire was plasma and heat at
• Relative to modern terms, of course
• Was the school of thought for chemistry until the 19th century

DALTON (1766-1844)

• Was color blind
• Studied color blindness
• Anticipated the law of multiple proportions

BILLIARD BALL MODEL 1802

• Atoms are the smallest unit of an element
• All atoms in an element have the same mass
• While not perfect, this model eventually led to the current atomic model
• Molecules were atoms arranged in the style of billiard balls

J. J. THOMSON (1856 - 1940)

• His student was Ernest Rutherford
• Got a Nobel prize in 1906 for discovering the electron
• Found first evidence of isotopes too

PLUM PUDDING MODEL 1904

• Electrons rotate around the atom in rings
• Electrons were surrounded by a "soup" of positive charge
• This is to combat the negative charge of electrons
• Was proven wrong by Thomson's own student, Rutherford

MILLIKAN (1868 - 1953)

• Won a Nobel prize
• Worked at university of Chicago
• Had a partner who let him take credit

MASS/CHARGE OF AN ELECTRON 1910

• Essentially verified the existence of subatomic particles
• Was tested using the oil drop experiment in 1909
• Showed that elements had their own electron charges

RUTHERFORD

• From New Zealand
• Paved the way for Chadwick
• Had element named after him
• Used gold foil experiment to make new atomic model

POSITIVELY CHARGED NUCLEUS 1909-1911

• Atoms have a small positively charged nucleus
• Most of the mass is in this nucleus
• Electrons orbit around this nucleus
• Made scientists realize that the atom isn't a single particle

CHADWICK (1891 - 1974)

• Worked on Manhattan project
• Was knighted for his achievements
• Became uncomfortable with large scale government funded experiments
• Retired in 1959

PROTON NEUTRON - 1932

• Neutrons were only theorized by Rutherford
• Heavier than protons, they allowed for elements heavier than uranium to be created in a lab
• Explained gaps or issues with the current model of atoms
• Neutrons and protons were bundled together in the nucleus