Colomac Semester One AP CHEM finals – Flashcards
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| two fundamental concepts of chemistry |
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| 1. matter is composed of various types of atoms 2. one substance changes to another by reorganizing the way atoms are attached to each other |
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| natural law vs. theory |
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| - natural law = summary of observed (measurable) behavior - theory = attempt to explain behavior (why it happens) |
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| fundamental SI units: mass, length, time, temperature, amount of substance, volume, electric current, luminous intensity |
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| kilogram (kg), meter (m), second (s), Kelvin (k), mole (mol), liter (L), ampere (A), candela (cd) |
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| mass vs. weight |
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| - mass = measure of the resistance of an object to a change in its state of motion - weight = force that gravity exerts on an object |
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| homogeneous vs. heterogeneous |
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| - homogeneous = visibly INDISTINGUISHABLE parts --> solution - heterogeneous = visibly DISTINGUISHABLE parts --> pure substance(constant composition) or 2+ solutions |
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| methods to seperate components into mixtures |
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| 1. distillation 2. filtration 3. chromatography = stationary phase (solid), mobile phase (liquid or gas) 4. paper chromatography = stationary phase is paper |
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| percent uncertainty |
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| if given A±B(uncertainty), percentage uncertainty = (B/A) x 100 |
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| calculating uncertainty 1. adding/subtracting 2. mutiplication/division 3. to a power |
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| 1. absolute uncertainties can be added 2. convert absolute uncertainty to percent uncertainties, then add 3. percent uncertainty times the power |
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| What to do with sigfigs when ADDING percent uncertainties during multiplication/division of absolute uncertainties? |
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| if added percent uncertainties are: - greater than or equal to 2%, 1 sigfig - less than 2%, no more than 2 sigfigs |
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| percent error |
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| [(|actual - theoretical|) ? theoretical] x 100 |
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| if % uncertainty > % error |
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| - random errors - instrument's fault - more trials will help improve data |
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| if % uncertainty < % error |
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| - systematic errors - your fault |
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| Law of Conservation of Mass |
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| - mass is neither created nor destroyed - experiments showed combustion involved oxygen, not phlogiston - Priestly, Lavoiser |
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| Law of Definite Proportion |
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| - a given compound always contains exactly the same proportion of elements by mass - constant composition of compounds - Proust |
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| Law of Multiple Proportions |
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| - molecular formula can be reduced to emperical formula |
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| Greeks questioned whether matter was: |
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| 1. continuous/infinitely divisible 2. composed of small, indivisible parts (Democritus of Abdera, Leucippos = coined the term atom) |
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| Greg Bauer/Paracelsus |
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| laid foundations of chemistry |
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| Boyle |
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| first chemist to perform truly quantitative experiments |
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| Dalton's Atomic Theory |
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| 1. each element is made up of tiny particles called atoms 2. the atoms of a given element are identical; the atoms of different elements are different in fundamental ways 3. chemical compounds formed when different elements combine 4. atoms themselves arent changed in chemical reaction, but reorganized |
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| isotope |
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| same number of protons, different number of neutrons |
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| if all atoms are composed of these same components, why do different atoms have different chemical properties? |
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| number and arrangement of electrons, therefore 3 of electrons possessed by given atom greatly affects its ability to interact with other atoms |
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| properties of atom: mass, # of protons, # of neutrons, # of electrons, |
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| protons + neutrons, atomic #, mass - protons unless its an isotope, # of protons unless it has a charge |
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| chemical vs covalent vs ionic BONDS |
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| - forces that hold atoms together, in general - share electrons... form molecules - transfer electrons... opposites attract |
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| radio isotope |
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| isotope that contains an unstable nucleus |
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| element will decay if... |
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| number of neutrons are too high or too low |
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| all atoms over __ protons are radioactive |
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| 83 |
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| alpha particles |
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| - positively charged - ionizing radiation: strips electrons off things they pass through - can't pass through paper or large clothing *4,2,He on right side |
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| beta particles |
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| - negatively charged - neutron decays to a proton and electron (N --> P+ + e- - smaller than alpha, therefore better at ionizing than alpha - cant pass through 3 mm aluminum foil *0,-1,e on right side |
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| gamma rays |
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| - no charge - not made of matter, PURE ENERGY = LOTS OF ENERGY, form of electromagnetic energy - usually emitted after transmutation (nucleus changed) - can't pass through 60 cm Al or 7 cm Pb *0,0,Y on right side |
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| electron capture |
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| - no charge - proton is turned into neutron (P+ e- --> N) - one of the inner-orbital electrons is captured by the nucleus - *0,-1,e on left side |
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| positron emission (B+) |
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| - positive charge - instead of 0,-1,e it is 0,+1,e - antimatter, destroyed when they encounter an electron - electron + positron = 2 gamma rays *0,+1,e on right side |
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| transmutations |
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| collision caused a change in nucleus, the problems you solve the math to figure out blank elements and yadayada - occurs in nuclear decay, fusion, and fission |
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| fission |
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| splitting a nucleus into 2 or more elements, some mass lost, breaks law of conservation of matter, chain reaction, e=mc^2 |
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| fusion |
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| when 2 nuclei combine, lots of energy can be released, occurs in stars |
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| Geiger Counter |
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| used to detect radioactive activity by measuring current that radiation produces in argon gas |
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| Ammonium, Carbonate, Chlorate, Chromate, Hydrogen Carbonate (bi), Hydroxide, Nitrate, Permanganate, Phosphate, Sulfate |
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| NH4+, CO32-, ClO3-, CrO42-, HCO3-, OH-, NO3-, MnO4-, PO43-, SO42- |
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| Relative Atomic Mass (Ar) |
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| mass of a single atom relative to C-12....isotope isotope mass / mass of carbon (which is 12) = Ar |
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| Relative Molecular Mass (Mr) |
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| sume of the Ar in a molecule |
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| percent composition |
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| % mass of element = (mass of element/mass of compound) x 100 |
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| molecular vs empirical |
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| real amount and reduced |
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| limiting reactant |
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| runs out first, SMALLER |
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| percent yield |
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| (actual yield/theoretical yield) x 100 |
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| percent to mass mass to mole divide by small multiply till whole.... method used when? |
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| determining molecular/emperical formulas |
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| grams to moles to moles to grams......method used when? |
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| stoichiometric caculations of limiting/excess reactants and products |
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| mass spectrometer |
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| instrument used to determine the masses of atoms and their isotopic composition by the deflection of ions in a magnetic field vaporization, ionization, acceleration, deflection, detection VIADD! |
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| to find excess reactant |
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| 1. start with limiting ~ COMPARED TO ~ excess |
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| theoretical yield |
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| maximum amount of a product formed when limiting reactant is completely used up |
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| to determine theoretical yield of a product |
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| start with limiting reactant ~ COMPARED TO ~ product calculating theoretical yield for |
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| polar molecule |
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| unequal charge distribution |
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| hydration |
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| + ends of water molecules attract to anions of ionic solid, and - ends of water molecules attract to cations of ionic solid |
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| when ionic substances (salts) dissolve in water, they break up into _______ |
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| INDIVIDUAL cations and anions |
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| when an ionic solid dissolves in water, ions become: |
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| 1. hydrated 2. dispersed |
