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specific gravity
- a measure of the mass of an object compared to the mass of equal volume of water
- =density w/o units
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reasons for uncertainty for measurements
- tolerance= construction of device
- human error= incorrect usage of device
- conditions= temperature, pressure, etc.
- malfunctioning equipment
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J.J. Berzelius
a Swedish chemist generally given credit for creating the modern symbols of elements
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atomic number = ? (the bottom number)
# of protons = # of electrons
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Latin names for:
Sodium
Gold
Silver
Potassium
Lead
Antimony
Iron
Tungsten
Tin
Copper
Mercury
- Sodium=Na, Natrium
- Gold=Au, Aurum
- Silver=Ag, Argentium
- Potassium= K, Kalium
- Lead=Pb, Plumbum
- Antimony=Sb, Stibinite
- Iron= Fe, Ferrum
- Tungsten=W, Wolfram
- Tin=Sn, Stannum
- Copper=Cu, Cuprum
- Mercury=Hg, Hydrogyrum
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Mixture
- 2 or more elements or coumpounds physically joined
- ex: Brass= Copper (Cu) + Zinc (Zn)
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Compound
- 2 or more elements chemically bonded to one another
- ex: H2O
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Mixtures: Two or more pure substances
a)homogenous
b)heterogenous
- a)uniform, constant composition Ex: salt water, shampoo
- b)non-uniform, varying composition Ex: granite, sand
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Democritus
- Greek philosopher: Matter is composed of indivisble particles called atoms
- atomos = "inidivisible"
- Plato & Aristotle disagreed b/c no evidence or experiments, he used theory
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Alchemy
- 1. Elixir of life
- 2. Transmutation: Lead into gold
- shifted from thought to observation and experimentation
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Laws that John Dalton based his Atomic Theory on:
- Laws Dalton based his Atomic Theory on:
- Law of Conservation of Mass
(Antoine Lavoisier): Mass is neither created nor destroyed Ex: 2H2+ O2=2H2O - Law of Constant Proportions (Joseph Proust): Compound always contains the same elements in the same proportions
- Law of Multiple Proportions (John Dalton): ratio of masses will remain constant for each compund
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J.J. Thomson
- -used a Cathode Ray (electrons) Tube and discovered the electron
- -determined charge to mass ratio of electron
- -cookie dough/ plum-pudding model, plums were the electrons
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Robert A. Millikan
- -Oil-Drop Experiment
- -determined charge of electron
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Ernest B. Rutherford
- -gold foil/alpha scattering experiment
- -discovered the helium nucleus, proton (contains most mass & is positive)
- -"planetary" atom model (electrons orbit nucleus) but it is wrong-first artificial transmutation
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Neils Bohr
- -Bohr model
- -only the H spectrum
- -worked in Manhattan Project
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James Chadwick
discovered neutron (late because w/no charge, it's hard to detect)
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a) nucleon?
b) nuclide?
c) radionuclide?
d) nuclear binding energy?
- a) a particle in the nucleus (neutron or proton)
- b) nuclide=nucleus
- c) unstable nucleus
- d) a strong force that holds protons and neutrons together
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mass number = ?
# of nucleons (neutrons+protons)
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the three hydrogen isotops
- 11 H = protium
- 21 H = deuterium
- 31 H = tritium
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Henri Becquerel
discovered radioactivity using photographic plates and uranium ore
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types of radioactivity
- alpha: nucleus of helium atom 4,2 He (through paper)
- beta: high speed electron emission from nucleus -1e (through 3mm Al)
- gamma ray: photon of high enery light: 00Y (through 3cm Pb)
- penetrating power: gamma>beta>alpha
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Stable nuclei
- 1) greater binding energy per nucleon
- 2) low atomic numbers with 1:1 ratio of neutrons to protons
- 3) even number of both neutrons & protons
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Mass defect
- where binding energy comes from
- the total mass of the stable nuclei > the sum of the masses of nucleons
- missing mass is converted to energy
- E=mc2
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how to determine half life
- No=how much
- x=half lives
- N/No=0.5x
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Transmutation
- -Bombardment: bombard a target nucleus with other particle or nuclei
- -product+nucleus->more than one product formed
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Fusion
- -combining smaller nuclei to form larger nuclei
- -which increases binding enery which increases stability
- -reactions take place at high temp (thermonuclear reactions)
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Fission
-large nucleus is broken into smaller nuclei + one or more neutron
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