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49 terms

chem exam1

STUDY
PLAY
Laws
concise verbal or mathematical statement of a relationship b/w phenomena that is always the same under the same condition. Ex. Newtowns second law of motion, force = mass times acceleration.
Theory
is a unifying principle that explains a body of facts and/or those laws that are based on them. Hypotheses that survive many experimental tests of their validity may evolve into theories. Are always constantly tested. Ex. Big bang theory.
Scientific Method
a systemic approach to research. Problem/question, Observation/research, Formulate a hypothesis, Experiment, Collect & Analyze results, Conclusion, Communicate the results
Matter
anything that occupies space and has mass
States
Solid: has both definite shape & a definite volume. The particles that make up a solid are very close together and many times are restricted to a very regular framework called a crystal lattice. Liquid: has a definite volume but no definite shape. It conforms to the shape of its container. The particles are moving much more that in the solid. They are usually clumps of particles moving relatively freely among other clumps. Gas: has neither a definite shape nor volume. It expands to fill its container. The particles are far apart, moving rapidly with respect to each other, and act independently of each other.
Extensive property
measurable value depends on how much matter is being considered. Examples: Mass, which is the quantity of matter in a given sample of a substance, is an extensive property. Volume, defined as length cubed, is another extensive property. Length, The value of an extensive quantity depends on the amount of matter.
Intensive property
measurable value does not depend on how much matter is being considered. Examples: Density, defined as the mass of an object divided by its volume, is an intensive property. Temperature, Color, Unlike mass, length, and volume, temperature and other intensive properties are not additive.
The boiling point of water on the Kelvin is
373K
Room temperature on the Kelvin, Celsius and Fahrenheit
298K, 25C, 77F
Scientific notation
is used to express very large & very small numbers.
1.234 kg
4 significant figures
606 m
3 significant figures
0.08 L
1 significant figure
2.0 mg
2 significant figures
0.00420 g
3 significant figures
8 oz
1 cup
16 oz
1 pint
32oz
1 quart
32 oz
0.946 L
128oz
1 gal
1 lb
454 grams
2.2 lb
1 kg
1 gal
3.784L
1cm3
1mL=1cc
1hr
3600seconds
1 inch
2.54 cm exactly
1mi
5280ft
1qt
0.946L
1qt
2pt
4qt
1gal
1cc
1cm3 = 1mL exactly
Democritus
The Greek philosopher postulated the existence of the atom.
Dalton 4 hypothesis he proposed to describe the nature of matter
Elements are composed of extremely small particles called atoms; All atoms of a given element are identical, having the same size, mass, & chemical properties. The atoms of one element are different from the other elements; Compounds are composed of atoms of more than one element. In any compound the ratio of the #s of atoms of any two of the elements present is either an integer or a simple fraction; A chemical reaction involves only the separation, combination, or rearrangement of atoms; it does not result in their creation or destruction.
The law of definite proportions was presented by
Joseph Proust.
What was the significance of Rutherford's experiments
He discovered the nucleus (not the neutron); By the gold foil method, measuring the scattering of alpha particles. Most of the particles passed through the gold foil w/little or no deflection. A few were deflected at wide angles. And occasionally, bounced back.; Quoted: "it was as incredible as if you had fired a 15-in shell at a piece of tissue paper and it came back and hit you"
How did this change the model of the atom proposed by Thompson
Rutherford reasoned that if Thomson's model was correct then the mass of the atom was spread out throughout the atom. Then, if he shot high velocity alpha particles (helium nuclei) at an atom then there would be very little to deflect the alpha particles. He decided to test this with a thin film of gold atoms. As expected, most alpha particles went right through the gold foil but to his amazement a few alpha particles rebounded almost directly backwards; These deflections were not consistent with Thomson's model. Rutherford was forced to discard the Plum Pudding model and reasoned that the only way the alpha particles could be deflected backwards was if most of the mass in an atom was concentrated in a nucleus. He thus developed the planetary model of the atom which put all the protons in the nucleus and the electrons orbited around the nucleus like planets around the sun.
Proton (+1)
mass: 1.673 x 10-24
Electron (-1)
1.675 x 10-24
Neutron (0)
9.109 x 10-28
The nucleus is the dense central core of the atom. What subatomic particles are contained within the nucleus?
Proton + neutron
Atomic Number (Z)
Number of Protons
Atomic Number
Number of Protons, Number of Electrons
Number of Neutrons
Mass Number (A) - Atomic Number
group I
Alkali (+)
group II
Alkaline Earth metals (+)
group 6A
(-) Other non-metals
group 7A
(-) Halogens
Group 8A
(-) Noble gases
Radioactivity
spontaneous emission of particles and/or radiation