chem test 2 Flashcards
covalent bond
pair of shared electrons
polar covalent bond
pair of shared electrons with the electron pair lying closer to 1 atom than to the other atom
electronegativity (Linus Pauling)
measure of how strongly atoms pull electrons
on periodic table, electronegativity increases to the right and up
Χ (chi) is the symbol
dipole moment
mu, is measure of HOW polar a polar bond is
resonance
when there is more than 1 way to arrange the double and/or triple bonds in the lewis structure. the actual structure is an average (hybrid) of different resonance structures
free radical
molecule or ion which has 1 or more unpaired electrons
formal charge (fc)
group# - # of bonds - # nonbonding electrons
electroneutrality principle (Linus Pauling)
if there is resonance, the preferred structure is the one with the smallest set of formal charges, and the one that has the most negative formal charges on the most electronegative atom
which bond is strongest
triple bond
which bond is longest
single bond
**VSPER
valence shell electron pair repulsion theory
electron pairs have negative charge, and try to spread themselves out as far as possible
equatorial positions
those in the main plane of molecules
axial positions
those above and below the main plane of molecules
polar bond
bond between atoms with different electronegativities
1 side of the bond is different from the other side of the bond
electron group
“things attached”
an electron, pair of electrons, 1 bond, multiple bonds
bonding group
a bond, single double or triple
lone pair
pair of electrons not involved in bonding
valence bond
pair of shared electrons produced by overlapping atomic orbitals from 2 different atoms
solution to bond angle issue for valence bonds
hybrid orbitals-linus pauling
sigma bond
pair of shared electrons mainly in the axis between the 2 atoms
pi bond
has the pair of shared electrons mainly above and below the bond axis
molecular orbitals
orbitals which extend over the whole molecule (or at least 1 bond) rather than just an atom
orbitals tell us where electron is likely to be
four principles of molecular orbital theory
of molecular orbitals=# of bonding atomic orbitals
bonding MO is always a lower energy than the antibonding MO
electrons are assigned to MOs using the Pauli principle and Hunds rule
usually, MOs are made from atomic orbitals of approximately the same energy
*molecular orbital antibonding because
the main electron density is outside the atom, pulling them apart
how many electrons in an orbital
2, one with spin up and one with spin down
diamagnetic
all electrons spin paired
paramagnetic
one or more electrons is NOT spin paired
bond order for molecular electron configuration
(electrons bonding MO - electrons antibonding MO) / 2
replacement reactions
HOH->NaOH
delta symbol
means heat supplied
decomposition reaction
(NH4)2Cr2O7(s)->NH3+CrO3+H2O (not balanced)
(aq)
aqueous/soluable
replacement reaction
Cu+AgNO3->Ag+Cu(NO3)2
up arrow
gas formed
double replacement reaction
AB+CD->AD+CB
stoichiometry
weight-weight relationships
limiting reagent (reactant)
the reactant that is all used up in a reaction, and determines when the reaction is stopped
percent yeild
actual/theoretical x 100
solution
homogenous mixture of 2 or more components
solvent
major component of the solution
solute
minor component
aqueous solution
the solvent is water
molarity
the way concentrations are measured, moles of solute per liters of solution
M=n/V
strong electrolyte
conducts electricity well
what kinds of solutes produce weak/strong electrolyte solutions
all salts are strong electrolytes (1 positive and 1 negative)
strong acids are strong electrolytes, all other acids are weak (acetic)
strong bases are strong electrolytes, all other bases are weak
strong acids
HNO3, H2SO4, HCl, HBr, HI, HClO4
strong bases
alkaline metal hydroxides, NaOH, KOH, LiOH, Ca(OH)2, Sr(OH)2 Ba(OH)2, Mg(OH)2
solubility rules
Na+, K+, NH4+, are soluble
NO3-, F-, C2H3O2- are soluble
SO4-2 are soluble EXCEPT Ba2+, Sr2+, Ca2+, Pb2+, Ag2+
Cl-, Br-, I- are soluble EXCEPT Ag+, Pb2+, Hg22+
everything else is insolube
metathesis reaction
double replacement, with at least one of the products insoluble, gas, or water
spectator ion
ion that appears on both sides of ionic equation
acid
anything that provides H+(aq) ions in solution
strong acid
strong electrolyte, conducts electricity, dissociated ions
polyprotic acid
multiple H
diprotic acid
2 H
base
substance that provides OH-(aq) ions in solution
acid base titration
acid is slowly added to base, or vice versa, until all has been neutralized. the molarity of the H+ must be equal to the molarity of the OH-
oxidation reaction
originally, reaction of anything with oxygen
currently, oxidation is a reaction in which the oxidation # of something increases
oxidation-reduction reaction
reaction in which the oxidation # of 1 element increases and the oxidation number of another element decreases
rules for determining oxidation numbers
- oxidation # of any element by itself is 0
- the oxidation # of a monatomic ion is it’s charge
- hydrogen has an oxidation # of +1, oxyden has a # of -2
- sum of the oxidation numbers in a molecule add up to 0
- sum of the oxidation numbers in an ion is it’s charge
