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Period: 322 to
The Greeks: Aristotle
-believed all objects were composed of a potential (matter) and a reality (form)
-believed universe had no beginning or end, and that it was eternal -
Period: 346 to 460
The Greeks: Plato
-used Empedocles element theory, and identified each elem. with reg. solid
Fire=tetrahedron Air=octahedron
Water=icosahedron Earth=cube
-all properies of matter could be deduced through pure thought w/o experimentation -
Period: 370 to 460
The Greeks: Democritus
-developed atomism to say that atoms were solid bodies that were infinite in #, size, and shape but not large enough to see w/naked eye
-thought evrythng emitted thin films of atoms and that our bodies received sensations from these -
Period: 420 to
The Greeks: Leucippus
-theorized that were 2 different elements: the "full" or "solid" and the "empty" or "void"
-theory atomism: an infinite # of atoms exist and are responsible for special props. of matter -
Period: 432 to
The Greeks: Empodocles
-believed all things were made of 4 elements; Earth, Fire, Water, and Air
-conducted experiment to show that air existed and wasn't only empty space
-reasoned, not experimentally, that light traveled in finite velocity -
Jan 1, 1492
Christopher Columbus
-discovers the New World -
Pilgrims
-Pilgrims land at Plymouth Rock, Massachusetts -
Period: to
John Dalton
-English chemist known for discovering Atomic Theory, but also discovered condition of Color Blindness -
Period: to
John Dalton
-Law of Multiple Proportions: if 2 elements 2gether form more than 1 compound, then ratios of the masses of the 2nd element, which combine with a fixed mass of the 1st element, will be ratios of samll whole #s
-Law of Definite Composition: compound always contains 2 or more elements combined in a definite proprtion by mass
-Law of Conservation of Mass: mass of closed system completly isolated remain constant overtime. Created idea that mass can't be created/destroyed, but can be re-arranged. -
War
-American and French begin siege of Cornwallis at Yorktown
-last battle of Revolutionary War -
Period: to
Hantaro Nagaoka
-interested in kinetic theory of gases and stability of Saturn rings
-presented idea at Tokyo society for mathematics/physics Dec. 1903 (announced discovery in British academic journal "philosophical magazine")
-idea led to question of electrons losing nrg when they are constantly moving
- in order to prove model, had to prove electrons were not losing nrg
-Bohr released detailed atom model that agreed with him. Proved that electrons were not losing nrg as went around positively charged nucleus, -
Period: to
Robert Milikan
-invented an Oil Drop experiment to study electrons (most famous for bcuz able to discover size of the charge of an electron)
-Oil Drop: atomizer sprays fine mist of oil drops ino chamber. Some droplets then fall through to lower level. Let fall until reached terminal velocity. Measured terminal velocity/calculated mass of each drop of oil using a formula. Directed rays to bottom to apply charge to fallen drops = electrons attach to the drops. Electric field make droplets hang in mid-air. -
Period: to
Ernest Rutherford
-studied under J.J. Thomson
-dealt with radioactive elements
-claimed all elements have half-lives and within a certain period of time these elements can turn into different stable elements
-reported two types of rays: alpha and beta
-discovered proton
-1st to make nuclear reaction -
Period: to
Niels Bohr
-1913, began study of atomic structure using Rutherford's model as a guide
-created new model that could be used to show the physical and chemical properies of the atom (shows nrg levels and sublevels) -
Period: to
Erwin Schrodinger
-QMM (Quantum Mechanical Model) is a model of atomic stucture based on mathematics and is accurate in locating where electrons are placed around the nucleus
-studied the eigenvalue problems in the physics of continuous media which paved way for his future work
-QMM determines allowed energies an electron can have and how to find the most probable location of an electron
-QMM is based on a theory that states that matter has properties relating with waves called the quantum theory -
Period: to
Erwin Schrodinger
-Heisenburg's Uncertainity Principle states that knowing the exact position and momentum, or speed of motion, of electrons at the same time is impossible
-complex shapes of orbitals are used in the QMM which indicate the volumes of space where electrons would most likely be located
-principal quantum #s are abbreviated with letter n, which label energy levels of an electron
-greater the value of n, greater the distance the electrons are from the nucleus, and the greater the energy -
Period: to
Louis De Broglie
-Einstein evaluated thesis "Research on the Theory Quanta", getting him a science degree
-got theory based on Plancks theory equation, which is E=hv
-believed that any moving particle/object had an associated wave
-theory showed that light was considered both a particle and a wave -
J.J. Thomson
-achieved most brillant work of his life=oranginal study of cathode rays culminating in the discovery of the electron -
Max Planck
-Quantum Theory explains the world on the smalles scale by looking at the stucture/behavior of atom and of subatomic particles assuming that all energy comes in tiny invisible bundles
-1900: E=h x f (higher energy levels--father from nucleus, to get higher--gain energy, ligth and radiation bundles called quanta, amount of energy measured in Joules (E), freguency in Hertz (f), H=planks constant in Joules per Hertz (j-second,j-s) Constant: 6.63 x 10^-34 j-s -
Period: to
Werner Heisenberg
-1927, came to conclusion
-states that you can not be completely certain of all characteristics (vector, speed, spin, mass) of a (sub) atomic particle at the same time, only probability of that being the case.
-this is bcuz in the act of measuring some aspects of it you alter tje others, as you would need a measurement tool that did not interact w/(sub) atomic particle. Results in that you can never be certain of something if you measure it. -
J.J. Thomson
-suggested model of the atom as sphere of positive matter in which electrons are positioned by electrostatic forces. Tried estimate # of electrons in an atom from measurements of the scattering of light, X, beta, and gamma rays. Found ISOTOPES. -
J,J, Thomson
-believed structure of atom is something like raison bread (Raison Bread Theory). Assumed body of atom spherical object containing N electrons confined in homogenous jellylike substance but realatively massive positive charge distribution whose total charge cancels that of the N electrons. Model sometimes called Plum Pudding Model. Only prob with theory was fact that electrons are not in homogenous gelatinous mixtures. -
Ernest Rutherford
-discovered atomic nucleus, and developed the atomic model -
World War I
-beginning of War World War -
Erwin Schrodinger
-discovered his wave equation which came from a dissatisfaction with Bohr's orbit theory -
James Chadwick
-proved existence of Neutrons
-smashed alpha particls into Be, and allowed radiation that was released to hit another target: paraffin wax. When the Be radiation hit H atoms in the wax, the atoms were sent into a detective chamber. In physics, known that omly particle having same mass as H atom could affect H in that manner (used radial to bomb H and N= atomic nucleus of N and H) (measured velocity of H and N nuclear) -
Erwin Schrodinger
-returned to University of Austria and studied problem of unifyinig gravitation and electromagnetism -
John F. Kennedy
-assassination of JFK