Chemistry fundamentals Flashcards
METRIC units
nano
10-9
micro
10-4
milli
10-3
centi
10-2
kilo
103
mega
106
1000 L =
1M3 (1 METER CUBED)
1 L =
1000 cm3
angstrom
10-10
what is density
mass /volume
usually expressed as kg/m3 but also can be in g/cm3 for the mcat know that the density of water is 1 g/cm3
how do we go from g/cm3 to kg/m3
multiply by 1000
what is the molecular formula?
it gives the identity and number of atoms in the molecule.
what is the empirical formula?
smallest whole numbers, it gives the ratio of atoms
common polyatomic atoms that we need to know for the MCAT
ammonium NH4+
Hydronium H30+
acetate
CH3C02-
BICARBONATE
HCO3-
CYANIDE
CN-
HYDROXIDE
OH-
NITRATE VS NITRITE
NO3-
NO2-
ITE = LESS OXGEN
PERCHLORATE
CL04-
CARBONATE
CO32-
SULFATE VS SULFITE
SO42- , SO32- (ITE= LESS OXYGEN)
PHOSPHATE
PO43-
THE MOLE
One mole of anything has 6.02 x10^23 entities. # moles = mass in grams /molecular weight
percent mass composition
a molecules emipirical formula can be used to determine the molecules percent mass composition.
we can also use the info about the percent composition to determine the compounds empirical formula.
concentration
molarity expresses the concentration of a solution in terms of moles of solute per volume in litres
what is the mole fraction?
fraction of moles of a given substance
- useful when more then 1 solute is present and often used when there are mixed gases
law of conservation of mass or matter
number of the atoms on the left side of the equation match the number on the right side.
Stoichiometric coefficients
precede each compound ! tell us in what poportion the reactants react and in what proportion are the products formed. tells us the ratios of the number of molecules ( moles) that apply to the combination of reactants and formation of products.
balancing equations
start with the most complex species in the reaction
what is the limiting reagent ?
the reactant we run out of first, it limits how much product the reaction can make. its not necesasarily the reactant that’s initially present in the smallest amount
the limiting reagent is always a ?
reactant
what is a catalyst?
substance that increase the rate of the reaction without being consumed.
what does the oxidation state or the number tell us?
it tells us about the atoms ownership if its valence electrons changes when it forms a compound
ionic compounds
have complete transfer of electrons.
what happens to covalent compounds ?
oxidation state of an atom is the charge it would have if the compound were ionic.
what are the rules for assigning oxidation?
rem : rule higher in the list will take precedence
1) the oxidation state of any element in its standard state is zero
2) the sum of oxidation states of the atoms in a neutral molecule must always be zero and the sum of the oxidation states of the atoms in an ion must always equal the ions charge
3) group 1 metals have a +1 oxidation state and group 2 metals have a +2 oxidation state.
4) fluorine has a -1 oxidation state
5) hydrogen has a +1 oxidation state when bonded to something more electronegative then carbon , but it has a -1 oxidation state when bonded to an atom less electronegative then carbon and a 0 oxidation state when bonded to carbon
6) oxygen has a -2 oxidation state ( exception: in peroxides H202, Na2o2) oxygen has a -1 state bc rule 3 and 5 are higher priority then rule 6.
7) the rest of the halogens have a -1 oxidation state and the atoms of the oxygen family have a -2 oxidation state
FONClBrISCH
lists elements in order from more electronegative (F) to the least electronegative (H).
so bonds from H to anything NOT found in this list will give H a -1 charge
transition metals
can have different oxidation states depending on the compound they are in. REM : METAL will never assume a - oxidation state.
