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Chem
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87
Chemistry
Undergraduate 2
09/08/2011

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Term
Rutherford's Gold Foil Experiment
Definition
bombarded positively charged particles (alpha particles) at a piece of gold foil and recorded the angles at which they rebounded to find the composition of an atom
Term
what is the ratio of electrons to protons in a neutrally charged atom?
Definition
1:1
Term
atomic number
Definition
number of protons in the nucleus
Term
mass number
Definition
#protons + #neutrons
Term
isotope of an element
Definition
an atom of that element with a different mass number (different number of neutrons)
Term
if Boron-11 is an isotope of Boron-10, how many neutrons does Boron-11 have?
Definition
6
Term
why will an ice cube made of deuterium not float in water?
Definition
deutrium is an isotope of hydrogen with two neutrons instead of two, so it's heavier than normal ice.
Term
what is the chemical difference between isotopes of the same element?
Definition
no chemical difference - only the mass is different.
Term
with what units do you measure atomic mass?
Definition
amus (atomic mass units)
Term
why is the weight of an element not going to be exactly the same as its mass number?
Definition
it's a weighted average according to how much of each isotope exists
Term
what is the most abundant isotope of carbon?
Definition
carbon-12 (closest number to its weight on the periodic table)
Term
if Boron is 20% Boron-10 and 80% Boron-11, how do we figure out its average mass?
Definition
.20(10.00) +.80(11.00) = average mass
Term
what is the unit for counting atoms or molecules?
Definition
mole
Term
Avogadro's number
Definition
6.022e23 --> the amount of particles in a mole (any substance)
Term
if 1 carbon atom weighs 12amu, how much does a mole of carbon weigh?
Definition
12grams
Term
if a mole of hydrogen is 1 gram, how much does 1 atom of hydrogen weigh?
Definition
1 amu
Term
2 helium atoms are 8 amu, so how much is 1 mole of helium?
Definition
4 grams
Term
rows in the periodic table
Definition
periods
Term
columns in the periodic table
Definition
groups
Term
transition metals
Definition
the middle rectangle
Term
characteristics of metals (5)
Definition
- conduct heat and electricity
- malleable
- ductile
- luster
- solids at room temperature (except for mercury, which is a liquid)
Term
where are nonmetals on the periodic table?
Definition
to the right of the staircase
Term
what is the one nonmetal that is liquid at room temperature?
Definition
Bromine
Term
where are the metalloids?
Definition
on the diagnal
Term
identify the metalloids
Definition
Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium
Term
how well do metalloids conduct?
Definition
decent semiconductors (better when heated) and good conductors when doped (small amount of impurity added)
Term
what state are metalloids?
Definition
solids
Term
particles in a mole
Definition
6.022e23
Term
Chemistry is the study of: (2)
Definition
- matter
- the reactions that transform one type of matter into another
Term
chemists are involved in either: (a)
Definition
- analysis
- synthesis
Term
analysis
Definition
examining what something is
Term
synthesis
Definition
creating/improving something new -- drugs, etc
Term
macroscopic
Definition
what you can see
Term
particulate
Definition
microscopic
Term
pure substance vs. mixture
Definition
pure substance: can't be broken down by physical change
mixture: CAN be broken down by physical change
Term
two kinds of pure substances
Definition
- elements
- compounds
Term
homogeneous mixtures vs. heterogeneous mixtures
Definition
homogeneous mixtures: uniform throughout on a molecular level
heterogeneous mixtures: not uniform throughout
Term
another word for a homogeneous mixture
Definition
solution
Term
homogeneous mixture ex:
Definition
saltwater, air
Term
heterogeneous mixture ex:
Definition
blood, salad
Term
elements vs. compounds
Definition
elements CANT be broken down by chemical change; compounds CAN
Term
chemical change
Definition
transformation of one substance into another
Term
# of elements in nature
Definition
94
Term
total number of elements
Definition
118
Term
the properties of compounds are ___________, and ______________ from the elements they are composed of.
Definition
the properties of compounds are UNIQUE and DIFFERENT from the elements they are composed of.
Term
ex: compound with different properties than its compositional elements
Definition
hydrogen gas is explosive, water is not
Term
key difference between elements and compounds
Definition
compounds can be broken down by chemical means; elements CAN'T
Term
does the order in which elements combine in a compound matter?
Definition
YES
Term
physical properties
Definition
color, melting/boiling point
Term
chemical properties
Definition
how a substance reacts/relates to other substances
Term
chemical properties
Definition
how a substance reacts/relates to other substances
Term
qualitative vs. quantitative properties
Definition
qualitative: can't measure (color, hard/soft, etc.)
quantitative: CAN measure (mass, density, etc)
Term
SI system: distance
Definition
meter
Term
SI system: mass
Definition
kilogram
Term
SI system: time
Definition
second
Term
SI system: temperature
Definition
Kelvin
Term
SI unit: amount of a substance
Definition
mole
Term
derived unit
Definition
two or more units together -- ex: meters/second^2
Term
convert: 1 m^3 --> mL
Definition
1 mL
Term
more density is _________ mass in _________ volume
Definition
more density is MORE mass in LESS volume
Term
intensive property vs extensive property
Definition
intensive property: doesn't matter how much you have, property howdoesn't change
extensive property: depending on how much of the substance you have, property changes
Term
how are temperature scales defined?
Definition
set two points; find temperature between them (ie. freezing point of water -- boiling point of water)
Term
what is zero degrees on the Kelvin scale?
Definition
absolute zero - where all particles stop moving (lose all their energy)
Term
how do you convert Celsius to Kelvin?
Definition
add 273 degrees
Term
how many significant figures? 10.15
Definition
4
Term
how many significant figures? .0015
Definition
2
Term
how many significant figures? .00150
Definition
3
Term
rewrite, margin of error, and significant figures: 3x10^2
Definition
300
- 1 significant figure
- margin of error is 100
Term
margin of error, scientific notation, significant figures: 300.0
Definition
- +/- .1
- 3.000x10^2
- 4 significant figures
Term
how do you add and subtract numbers?
Definition
answer has the same number of DECIMAL PLACES as component figure with fewest
Term
how do you multiply and divide?
Definition
answer has the same amount of SIGNIFICANT FIGURES as the component number with fewest
Term
exact numbers (ex: number of seconds in a minute) are treated as if they have how many significant figures?
Definition
infinite
Term
how did radioactivity prove that atoms are made from smaller particles?
Definition
observed atoms spontaneously breaking up into smaller pieces
Term
Thompson's Cathode Ray Tube Experiment determined:
Definition
the charge to mass ratio of an electron
Term
Thompson's Cathode Ray Tube Experiment consisted of
Definition
charged plates at opposite ends of a glass vacuum tube -- manipulating the resulting stream of electrons using magnetic fields, proving they had mass and charge
Term
Millikan's Oil Drop Experiment determined:
Definition
the exact mass and charge of an electron
Term
Millikan's Oil Drop Experiment:
Definition
fine droplets of negatively charged oil (using x-rays) into a chamber with a negatively charged floor and a positively charged ceiling until the droplets hovered
Term
condensation: physical or chemical change?
Definition
physical
Term
color change with bleach: physical or chemical change?
Definition
chemical
Term
Alkali metals react with water to produce:
Definition
hydrogen and alkaline solutions
Term
because of their reactivity, alkali metals are found in nature only in ___________
Definition
compounds
Term
makes up 3/4 of the earth's atmosphere
Definition
Nitrogen
Term
nitrogen fixation
Definition
making compounds from atmospheric nitrogen
Term
what is a barrier to nitrogen fixation?
Definition
need extreme conditions (like high temperatures) in a lab
Term
two allotropes of P
Definition
white and red phosphorus
Term
chalcogens
Definition
sulfur, selenium, tellurium
Term
halogens all exist as ________ molecules
Definition
diatomic
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