chapter 3 Flashcards
The 6 basic SI metric units
Meter (m) for length Kilogram (Kg) for mass second(s) for time mole (mol) for amount of substance Kelvin (K) for temp Ampere (A) for electric current *pg 34*
SI for energy
Joule (kg*m^3)
pg 34
6 power of ten prefixes
nano- (n) 10^-9 micro- (µ) 10^-6 milli- (m) 10^-3 centi- (c) 10^-2 Kilo (k) 10^3 mega (M) 10^6 *pg34*
the Angstrom
symbol: Å.
a unit of length equal to 10^-10 m
it is convenient because atomic radii and bind lengths are typically around 1 to 3 Å
pg 35
order of magnitude
factor of 10
(so if it asks by how many orders of 10 something is bigger or smaller it is asking by how many factors of 10 it is smaller of bigger)
pg 35
density (conversion factor)
mass per volume ρ = mass/volume = m/v expressed in Kg/m^3 or g/cm^3 g/cm^3 x 1000 = Kg/m^3 or vice versa *pg 35*
the density of water
1 g/cm^3 or 1000 kg/m^3
molecule
when two or more atoms form a covalent bond they create a molecule
pg 36
Molecular formula
gives the identities and numbers of the atoms in the molecule. ( for ex C4H4N2)
PG36
empirical formula
the smallest whole numbers that gives the same ratio of atoms from the molecular formula. so we have to divide all the subscripts in the molecular formula by their greatest common factor to get the empirical formula
example: C6H12O6 becomes CH2O
* pg36*
Polyatomic ions
Ammonium (NH4+) Hydronium (H3O+) Acetate (AcO-) (CH3CO2-) Bicarbonate (HCO3-) Cyanide (CN-) Hydroxide (OH-) Nitrate (NO3-) Nitrite (NO2-) Perchlorate (CLO4-) Carbonate (CO3 2-) Sulfate (SO4 2-) Sulfite (SO3 2-) Phosphate (PO4 3-) *pg37*
unit for atomic weight
Atomic mass unit (amu)
1 amu is equal to exactly 1/12 the mass of an atom of Carbon 12 (12C)
Molecular weight (MW) is the more commonly used term in substitute of this
*pg37
moles formula
mol = mass in grams/ MW
formula weight
is the same as molecular weight
*pg38
how to find percentage composition by mass
each element’s mass divided by the molecular weight of the compound
*pg39
steps to find empirical formula
- find the percentage composition
- use the percentage composition as mass (ex: if there was 60% C in C4H4N2 then there is 60g of C) unless stated otherwise
- find the moles using the mass
- divide the moles of each element by the moles of the element with the most moles
- the ratio you find will be the subscript. (if you divided the moles of Fe/O and you get 2/3 the answer will be Fe2O3)
* pg40
Molarity
symbolized by M. expresses the concentration of a solution in terms of moles of solute per volume (in L) of solution
M = #of mol/#liters of sol
denoted by being in [ ]
*pg 42
Mole fraction
simply expresses the fraction of moles of a given substance relative to the total moles in a solution
mol fraction = #moles of substance/ total #moles in solution
*pg 42
Law of conservation of mass/matter
the amount of matter does not change in a chemical reaction. the amount of matter on the right side of the arrow should equal the left side
*pg42
what does Δ mean on top of an arrow in a reaction
it means that there’s heat added to the reactants (the reactants are heated) the word ‘heat’ could also be written instead of the symbol
*pg46
catalyst
a substance that increases the rate of a reaction without being consumed. the presence of a catalyst is indicated by writing it below the arrow in a reaction
*pg46
oxidation state or oxidation number
meant to indicate how the atom’s ‘ownership’ of its valence electrons changes when it forms a compound. giving up ownership results in a more positive oxidation state while accepting it results in a more negative state
*pg47
ionic compounds vs covalent compounds’ oxidation states
ionic compounds are considered to involve the complete transfer of electrons.
for covalent compounds the oxidation state of an atom is the charge it would have if the compound were ionic
*pg47
the 7 rules for assigning oxidation states
1) the oxidation state of any element in its standard state is 0
2) the sum of the oxidation states of the atoms in a neutral molecule must always be 0, and for ions it must equal the ion’s charge
3) group 1 metals have a +1 oxidation state, and group 2 metals have a +2
4) Fluorine has a -1
5) Hydrogen has a +1 when bonded to something more electronegative than C, a -1 when bonded to an atom less electronegative than a C, and 0 when bonded to C
6) oxygen has a -2 oxidation state
7) the rest of the halogens have a -1, and the atoms of the oxygen family have a -2
- rules 3 and 5 have a higher priority than 6, so something like H202 or Na2O2, Oxygen will have a -1 oxidation state
- metals can never have a negative oxidation state
*pg47
Mnemonic for the order of electronegativities
FONClBrISCH (pronounced fawn-cull-brish)
in the order of the most electronegative to least electronegative
(If H is bound to something not in this list it will have a state of -1)
*pg47
