CHEM 105 Test 3 (Ch. 6-8) Flashcards
paramagnetic
unpaired e-s
the valence electrons of the atoms in a molecule reside in
quantum-mechanical atomic orbitals; orbitals can be s,p,d,f or hybrid combos of these
a chemical bond results from
the overlap of two half-filled orbitals and spin-pairing of the two valence electrons
to interact, the orbitals must either
be aligned along the axis b/w the atoms or be parallel to each other and perpendicular to the interatomic axis
hybridization
mixing different types of orbitals in the valence shell to make a new set of degenerate orbitals
the number of hybrid orbitals formed equals
the number of standard atomic orbitals combined
the particular kind of hybridization that occurs is the one that
yields the lowest overall energy for the molecule
sp3 hybridization
atom with 4 electron groups around it; tetrahedral geometry; 109.5* angles between hybrid orbitals; atom uses hybrid orbitals for all bonds and lone pairs
sp2 hybridization
atom with 3 electron groups around it; trigonal planar system; 120* bond angles; flat; atom uses orbitals for sigma bonds and lone pairs and uses nonhybridized orbital for pi bond
sigma bond
results when the interacting atomic orbitals point along the axis connecting the two bonding nuclei; either standard atomic orbitals or hybrids
pi bond
results when the bonding atomic orbitals are parallel to each other and perpendicular to the axis connecting the two bonding nuclei; between unhybridized parallel p orbitals
? bonds are stronger than ? bonds
sigma; pi
overlap between a hybrid orbital on one atom with a hybrid or nonhybridized orbital on another atom results in a ? bond
sigma
overlap between unhybridized p orbitals on bonded atoms results in a ? bond
pi
? bonds require the breaking of the interaction between the orbitals to rotate
pi
sp hybridization
atom with 2 electron groups; linear shape; 180* bond angle; atom uses hybrid orbitals for sigma bonds or lone pairs and uses nonhybridized p orbitals for pi bonds
sp3d hybridization
atom with five electron groups; trigonal bipyramidal; seesaw, T-shaped, linear; 120* and 90* bond angles; ues empty d orbitals from valence shell; d oritals used to make pi bonds
sp3d2 hybridization
atom with six electron groups; octahedral electron geometry; square pyramidal, square planar; 90* bond angles; use empty d orbitals from valence shell to form hybrid; d orbitals used to make pi bonds
2 e- groups
linear e- geometry; sp hybridization
3 e- groups
trigonal planar e- geometry; sp2 hybridization
4 e- groups
tetrahedral e- geometry; sp3 hybridization
5 e- groups
trigonal bipyramidal; sp3d hybridization
6 e- groups
octahedral; sp3d2 hybridization
valence bond theory doesn’t account for
magnetic behavior of O2; delocalization of e-s
Molecular Orbital (MO) Theory
applies Shrodinger’s wave equation to the molecule to calculate a set of molecular orbitals; in this treatment, the e-s belong to the whole molecule, so the orbitals melong to the whole molecule (delocalization)
Linear Combination of Atomic Orbitals (LCAO)
atomic orbitals of the atoms add together to make molecular orbitals; b/c the orbitals are wave functions, the waves can combine either constructively or destructively
when the wave functions combine constructively, the resulting molecular orbital has (more/less) energy than the original atomic orbitals; called ?
less; called a bonding molecular orbital (designated sigma or pi)
when the wave functions combine destructively, the resulting molecular orbital has (more/less) energy than the original atomic orbital; called?
more; called an antibonding molecular orbital (designated sigma* or pi*)
electrons in bonding MOs are (stabilizing/destabilizing) and have (lower/higher) energy than the atomic orbitals
stabilizing, lower
electrons in antibonding MOs are (stabilizing/destabilizing) and have (lower/higher) energy than the atomic orbitals
destabilizing, higher
electrons in antibonding orbitals ? stability gained by electrons in bonding orbitals
cancel
bond order =
1/2 (# bonding e-s - #antibonding e-s)
higher bond order means
stronger and shorter bonds
if bond order = 0, then the bond
will not form
if all e-s are paired, the substance is
diamagnetic
when the combining atomic orbitals are identical and of equal energy, the contribution of each atomic orbital to the molecular orbital is
equal
when the combining atomic orbitals are different types and energies, then
the atomic orbital closest in energy to the molecular orbital contributes more to the molecular orbital
the more electronegative an atom is, the
lower in energy its orbitals are
lower energy atomic orbitals contribute more to the ? MOs
bonding
higher energy atomic orbitals contribute more to the ? MOs
antibonding
nonbonding MOs remain ? on the atom donating its atomic orbitals
localized
when many atoms are combined together, the atomic orbitals of all the atoms are
combined to make a set of molecular orbitals, which are delocalized over the entire molecule
physical changes
changes that alter only the state or appearance, not composition; identity of the atoms or molecules does not change
chemical changes
changes that alter the composition of matter; atoms rearrange, transforming the original substances into different substances
percent yield =
actual / theoretical x 100%
limiting reactant/reagent
the reactant that makes the least amount of product
theoretical yield
the amount of product that can be made from the limiting reactant
reactant in excess
any reactant that occurs in a quantity greater than is required to completely react with the limiting reactant
a combustion reaction involves
a reaction of a substance with O2 for form one or more oxygen-containing compounds; products are water and heat (energy)
common reaction for alkali metals is
with halogens
2M + X2 -> 2MX
the alkali metals react vigorously with water to form
dissolved alkali metal ion, the hydroxide ion, and hydrogen gas 2 M (s) + 2 H2O (l) -> 2 M+ (aq) + 2 OH- (aq) + H2 (g)
the halogens react with metals to form ? and hydrogen to form ?
metal halides, hydrogen halides
homogeneous mixtures are called
solutions
the minor component of the solution is called the
solute
the major component of the solution is called the
solvent
dilute solutions have a ? amount of solute compared to solvent
small
concentrated solutions have a ? amount of solute compared to solvent
large
Molarity (M) =
moles solute / Liter of solution
equation to determine change in concentration or volume for solutions
M1V1 = M2V2
electrolytes
materials that dissolve in water to form a solution that will conduct electricity
nonelectrolytes
materials that dissolve in water to form a solution that will NOT conduct electricity
strong electrolytes
completely dissociate into ions
weak electrolytes
partially dissociate into their ions
strong acid
dissociates completely in water; would be a strong electrolyte
weak acid
dissociates partially; would be a weak electrolyte
most molecular compounds dissolve in water as
intact molecules > nonelectrolyte solution
compounds containing the following ions are generally soluble
Li+, Na+, K+, NH4+, NO3-, and C2H3O2-
Cl-, Br-, and I- except for with Ag+, Hg22+, Pb2+
SO42- except with Sr2+, Ba2+, Pb2+, Ag+, or Ca2+
compounds containing the following ions are generally insoluble
OH- and S2- except with Li+, Na+, K+, NH4+, Ca2+, Sr2+, or Ba2+
CO32- and PO43- except with Li+, Na+, K+, or NH4+
precipitation reactions
reactions in which a solid forms when two solutions are mixed
the insoluble product is called a
precipitate
predicting precipitation reactions
- determine what ions each of the aqueous reactants has
- determine formulas of possible products
- determine the solubility of each product in water
- if neither product will precipitate, write “no reaction” after the arrow
- if products are insoluble, write (s) after formula to indicate solid; if soluble, write (aq) to indicate aqueous
- balance the equation
molecular equation
an equation showing the complete neutral formula for each compound in the aqueous reaction as if they existed as molecules
complete ionic equations
equations that describe the material’s structure when dissolved
spectator ions
ions that do not participate in the reaction
net ionic equation
differs from a complete ionic equation because it does not include the spectator ions
acids
molecular compounds that form H+ when dissolved in water; composed of Hydrogen, usually written first in their formulas, and 1+ nonmetals, written second
Arrhenius Definitions:
acid: substance that produces H+
base: substance that produces OH-
polyprotic acids
acids that contain more than one ionizable proton (H+) and release them sequentially
binary acids
have H+ cation and nonmetal anion
oxyacids
have H+ cation and polyatomic anion
how to name a binary acid
hydro + (base name of nonmetal + -ic) + acid
how to name an oxyacid
if ends in -ate, change suffix to -ic
if ends in -ite, change suffix to -ous
(follow binary rules aside from this)
neutralization reaction
an acid reacts with a base, and the two neutralize each other, producing water; the anion from one reactant combines with the cation of another
a neutralization reaction is completed when
moles of acid = moles of base
the endpoint of titration
when the indicator color changes - the equivalence point
gas-evolution reaction
a gas forms, resulting in bubbling; many are also acid-base reactions
types of compounds that undergo gas-evolution reactions
sulfides > H2S
carbonates & bicarbonates > CO2
sulfites and bisulfites > SO2
ammonium > NH3
oxidation-reduction reactions
the reactions in which electrons are transferred from one reactant to the other
atoms that lose electrons are being
oxidized
atoms that gain electrons are being
reduced
oxidation will (increase/decrease) the oxidation state
increase
reduction will (increase/decrease) the oxidation state
decrease
rules for assigning oxidation states
- free elements have an oxidation state = 0
- monatomic ions have an oxidation state equal to their charge
- a) the sum of the oxidation states of all the atoms in a compound is zero
b) the sum of the oxidation states of all the atoms in a compound is zero - a) Group I metals have an oxidation state of +1 in all their compounds
b) Group II metals have an oxidation state of +2 in all their compounds - in their compounds, nonmetals have oxidation states according to the table
oxidation state of fluorine
-1
oxidation state of hydrogen
+1
oxidation state of oxygen
-2
oxidation state of Group 7A
-1
oxidation state of Group 6A
-2
oxidation state of Group 5A
-3
oxidizing agent
the reactant that oxidizes an element in another reaction; contains the element that is reduced
reducing agent
the reactant that reduces an element in another reaction; contains the element that is oxidized
an activity series table lists metals in order of (increasing/decreasing) tendency to lose e-s
decreasing; so higher up is more likely to be oxidized and lower down is more likely to be reduced
AgCl, HgCl2, PbCl2
AgBr, HgBr2, PbBr2
AgI, HgI2, PbI2
insoluble
SrSO4, BaSO4, PbSO4, Ag2SO4, CaSO4
insoluble
LiOH, NaOH, KOH, NH4OH, Ca(OH)2, Sr(OH)2, Ba(OH)2
Li2S, Na2S, K2S, (NH4)2S, CaS, SrS, BaS
soluble
Li2CO3, Na2CO3, K2CO3, (NH4)2CO3
Li3PO4, Na3PO4, K3PO4, (NH4)3PO4
soluble
