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Prelim 1
N/A
35
Chemistry
Undergraduate 3
09/28/2012

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Term
Known Observations before Dalton
Definition
1. most natural materials were mixtures of pure substances
2. pure substances are elements or compounds
3. a given compound always contains the same relative mass of the elements
Term
Dalton's Atomic Theory
Definition
1. elements are made up of small particles called atoms
2. all atoms of a given element are identical
3. the atoms of one element are different than atoms of another element
4. atoms of one element can combine with atoms of another element to form compounds
5. atoms are indivisible in chemical processes (chemical reactions invovle exchanging atoms between compounds)
Term
JJ Thomson's 3 Experiments
Definition
1. use magnets to bend/move ray through little hole in cathode ray tube so he can count the charge (**shows that ray and charge are the same thing)
2. use cathode ray tube with battery to determine if charge was + or - (**confirms charge is -)
3. Try to figure out how heavy the charges are by using magnets of varying strength (**weak magnets move the beam, therefore what is in the beam is very, very light OR heavily charged --> weakness of 3rd experiment)
DISPROVE DALTON'S THEORY
Term
Thomson's Model of the Atom
Definition
"Plum Pudding Model"
+ and - charges mixed together in a ball
Term
Robert Millikan
Definition
-oil drop experiment
-succeeded in measuring charge of electron! by measuring charge on outside of oil drops
-e=1.6 x 10^-19 coulombs
Term
Ernest Rutherford
Definition
-alpha particles with gold foil experiment
-only some go through, others deflect
-concludes that there are 2 areas of an atom --> must have big empty space and there must be somewhere that is very dense with + charge
Term
Rutherford's model of the atom
Definition
-like normal model today
-except electrons aren't orbiting, just hanging out
-dense core with protons
Term
Frederick Soddy
Definition
-discovered isotopes
-said there were elements that were already known that had different radioactive properties yet identical chemical properties --> how it reacted with other elements
Term
James Chadwick
Definition
-discovered neutrons
-magnet/charge had no effect on particle that came out of Beryllium foil
Term
James Chadwick
Definition
-discovered neutrons
-magnet/charge had no effect on particle that came out of Beryllium foil
Term
Niels Bohr's Atom Model
Definition
-levels in concentric circles outside of nucleus
-"quantized"--> when electron moves from one orbital to another
-correct -> electrons at different distances/levels of energy
-wrong -> too 2 dimensional
Term
Erwin Shroedinger
Definition
-different electron orbitals
-s, p, d
-spherical, dumbbells, clover, dumbbells with belt
Term
Binnig and Rohrer
Definition
-discovered shape of electron
-used needle with current
Term
First Quantum Number
Definition
-n
-what shell e- is in --> how close/far from nucleus
-must always be + integer, 1, 2, 3, 4...
Term
Secondary Quantum Number
Definition
-L
-values of 0, 1, 2, 3, ... (n-1)
-L values tell you the shape of the orbital
Term
Third/Magnetic Quantum Number
Definition
-Me
-can have following values, -L, -L+1, -L+2, ... -1, 0, 1, ... L-2, L-1, L
-tells you how many identical orbitals in shell
Term
Fourth Quantum Number
Definition
-Ms
-Uhlenbeck and Goudsmit
-electrons have "spin"
Term
Hund's Rule
Definition
orbitals tend to be more stable when either half filled or fully filled
Term
Johann Wolfgange Doebereiner
Definition
-Law of Triads
Term
de Chancourtois
Definition
-Telluric Helix (1st periodic table)
-organized by mass and chemical reactivity
-"The properties of the elements are the properties of the numbers"
Term
Lothar Meyer
Definition
-first one to hit on periodicity
-volume vs. mass "Periodic Table"
Term
Dmitri Mendeleev
Definition
-open spaces in periodic table --> SHOULD be an element (predicting periodicity)
-Errors/Shortcomings
1. offset transition metals because he didn't know where to put them
2. missed a whole group --> Noble Gases because none are known and doesn't predict they will be found
3. people interpreted that there were elements missing between H and Li (too MANY)
Term
William Ramsay
Definition
-discovered Noble Gases
-heats minerals to find them
Term
Wilhelm Roentgen
Definition
-discovered x-rays
-metal at end of tube -> never would have discovered x-rays if there was no metal
Term
Antoin Henri Becquerel
Definition
-rock experiment --> rock emits energy! (U)
-discovers "radioactive decay"
Term
Alpha Particles/Alpha Decay
Definition
-helium nucleus without e- --> +charged
-relatively massive
-won't penetrate sheet of paper
-could be emitted with other things, like gamma rays
Term
Beta Decay
Definition
- "-" charge
-relatively "massless"
-"electron"--> not normal electron because the origin is the NUCLEUS
-1/2 cm lead will protect you
Term
Gamma Rays
Definition
-NOT a particle
-can accompany alpha and beta decay
-pure energey
-10 cm lead for protection
Term
Positrons
Definition
-VERY rare and dangerous
-largely produced by carbon-11, potassium-40, nitrogen-13, oxygen-15, chlorine-18, iodine-121
Term
Electron Capture
Definition
-nucleus sucks in electron
-proton + electron = neutron
-x-rays
Term
X-Rays
Definition
Sources:
1. electron capture
2. e- shot at a larger nucleus (metal) --> Roentgen
Term
Fissile
Definition
-will break apart in presence of neutrons
-decays/unstable
Term
Fertile
Definition
can be prompted to decay under right circumstances
Term
Enrico Fermi
Definition
-accomplished NUCLEAR FISSION (first to do so)
-creates first self-sustaining nuclear reaction --> gets product neutrons to continue the cycle
Term
PWR Nuclear Plant
Definition
-Pressurized Water Reactor
-core --> enriched uranium with H20 and D20
-D20 --> "heavy water"/deuterium
1. acts as moderator to slow down neutrons to induce more fission
2. acts as heat transfer agent
-control rods --> cadmium metal (as reaction becomes self sustaining)
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