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90 Cards in this Set
- Front
- Back
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systematic error |
produces values either ALL higher or ALL lower than actual value. Often caused by faulty device or consistent mistake in taking a reading. |
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random error |
produces values higher AND lower than actual value. Always occurs, but size depends on measurer's skill and instrument's precision. |
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mixture |
composed of two or more substances that are PHYSICALLY intermingled, NOT chemically combined |
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law of mass conservation |
total mass of substances does not change during a chemical reaction |
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mass fraction |
mass of element X in compound A/mass of compound A |
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cathode rays |
helped with discovery of electrons. Cathode rays consist of negatively charged particles found in all matter. |
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nucleus |
contains all positive charge and essentially all mass of an atom. |
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mass number |
total number of protons and neutrons |
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isotope |
atom of certain element with different numbers of neutrons and therefore has different mass number.
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atomic mass unit |
how to measure the mass of an atom
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mass spectrometry |
method for measuring relative masses and abundances of atomic-scale particles very precisely |
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atomic mass |
average of the masses of an atoms naturally occurring isotopes |
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periods |
horizontal rows on periodic table |
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groups |
vertical columns on periodic table |
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periodic table of elements |
modern version is based off of Mendeleev's version |
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metals |
large lower left portion of periodic table |
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nonmetals |
small upper right portion of periodic table |
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metalloids |
staircase elements |
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ionic compounds |
formed from transfer of electrons from one element to another |
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covalent compounds |
sharing electrons between atoms of different elements |
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chemical bonds |
forces that hold the atoms together in a compound |
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ions |
charged particles that form when an atoms gains or loses one or more electrons |
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binary ionic compound |
simplest type of ionic compound, composed of 2 elements. typically when metal reacts w/ nonmetal |
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cation |
positively charged ion |
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anion |
negatively charged ion |
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monatomic ion |
cation or anion derived from a single atom |
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chemical formula |
element symbols and numerical subscripts show type and number of each atom in substance |
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hydrate |
ionic compounds with specific number of water molecules in each formula unit |
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formula unit |
relative numbers of cations and anions in compound |
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binary covalent compounds |
typically formed by 2 nonmetals |
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molecular formula |
uses element symbols and numerical subscripts to give the actual number of each element in a molecule of the compound (H2O) |
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structural formula |
shows the relative placement and connections of atoms in the molecule. ex: electron dot formula or bond-line formula |
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ball and stick model |
shows atoms as balls and bonds as sticks, and angles between the bonds are accurate |
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space-filling model |
accurately scaled up image of molecule, shows relative size of atoms and relative distances between nuclei |
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heterogeneous mixture |
ex: oil and water; can see separation |
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homogeneous mixture |
can't see separation, ex: blood, coffee also known as a solution |
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aqueous solution |
mixed w/ water |
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molar mass (M) |
mass per mole of its entities (atoms, molecules, formula units) units (g/mol) |
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empirical formula |
shows lowest whole number of moles, and thus the relative number of atoms, of each element in compound |
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molecular formula |
actual number of atoms of each element in molecule |
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combustion analysis |
measures amounts of carbon and hydrogen in a combustible organic compound |
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isomer |
different compounds, same molecular formula |
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overall (net) equation |
1. write sequence of balanced equations 2. adjust the equations arithmetically to cancel common substances 3. add the adjusted equations to obtain overall balanced equation |
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limiting reactant |
(limiting reagent), element that is completely used up |
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theoretical yield |
amount of product calculated from the molar ration in the balanced equation (never actually obtained) |
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actual yield |
amount of product ACTUALLY obtained |
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solute |
smaller quantity in solution that's dissolved into the solvent |
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solvent |
larger quantity in solution (water in any aqueous solution) |
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polar nature of water |
1. uneven charge distribution 2. bent molecular shape 3. molecular polarity (region near O is partially negative, region between H atoms is partially positive) |
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electrolyte |
substance that conducts a current when dissolved in water |
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nonelectrolyte |
when aqueous solution of a substance does not conduct electric current |
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Molarity |
most common unit of concentration (mol solute/L solution) |
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concentration |
quantity of solute dissolved in a given quantity of solution (or of solvent) |
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molecular equation |
reveals least about the species that are actually in solution |
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total ionic equation |
shows all the soluble ionic substances (more accurate) shows their charges |
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spectator ions |
ions that appear unchanged on both sides of equation, aren't in the actual chemical change but are present only as part of the reactants |
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net ionic equation |
eliminates spectator ions and shows only the actual chemical change |
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precipitation reaction |
two soluble ionic compounds react to form insoluble product (precipitate) |
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acid-base reaction (neutralization reaction) |
acid reacts w/ base
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acid |
substance that produces H+ ions when dissolved in water |
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base |
substance that produces OH- ions when dissolved in water |
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acid |
molecule or ion that donates a proton |
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base |
molecule or ion that accepts a proton |
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equivalence point |
occurs when amount of H+ ions in original volume of acid has reacted w/ same amount of OH- ions |
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end point |
tiny excess of OH- ions changes the indicator permanently to its basic color |
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redox reaction |
movement of electrons from one reactant to another |
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oxidation |
LOSS of electrons |
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reduction |
GAIN of electrons |
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oxidizing agent |
species DOING the oxidizing (causing electron loss)
is reduced |
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reducing agent |
species DOING the reducing (causing electron gain)
is oxidized |
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oxidation number |
charge the atom would have IF electrons were transferred completely, NOT shared |
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decomposition redox reactions |
-compound forms 2 or more products -reactants absorb enough energy for one or more bonds to break -usually by heat (thermal) or electricity (electrolytic) |
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pressure |
force/area |
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gas volume |
-changes significantly w/ pressure -changes significantly w/ temperature |
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gases |
-flow freely -relatively low densities -form a solution in any proportions |
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barometer |
-measures atmospheric pressure
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Boyle's law |
V = 1/P -volume inversely proportional to pressure |
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Charles' Law |
P = T, V = T -pressure proportional to temperature |
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ideal gas |
gas that exhibits linear relationships among volume, pressure, temperature, and amount |
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Avogadro's Law |
V = n |
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STP (standard temperature and pressure) |
0 degrees Celsius (273 K), 1 atm (760 torr) |
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standard molar volume |
22.14 L |
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ideal gas law |
PV = nRT |
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universal gas constant |
R = 0.0821 |
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partial pressure |
each gas in mixture exerts partial pressure |
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Ptotal = P1 + P2 + P3 + ... |
Dalton's law of partial pressure |
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mole fraction (X) |
each component in a mixture contributes a fraction of the total number of moles in the mixture |
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kinetic-molecular theory |
1. volume of each particle in gas is so small compared to volume of whole sample that it is assumed to be zero; each particle is a point of mass 2. particles are in constant, random, straight-line motion except when they collide with other particles or container 3. collisions are ELASTIC, colliding molecules exchange energy but don't lose any through friction |
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effusion |
rate of effusion = 1/ sqrtM (rate at which gas escapes through tiny hole in its container) |
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diffusion |
movement of one gas through another rate of diffusion = 1/sqrtM |
