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77 Cards in this Set

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What is molecular geometry?
general shape of a molecule. the five types are linear, trigonal planar, tetrahedral, trigonal bypiramidal, and octahedral.
What is the VSEPR model?
Valence-shell electron-repulsion. States that shapes of molecules and ions are predicted by the fact that electrons prefer to be kept as far away from each other.
IF an atom has two pairs of electrons...
Its is linear. the atoms are at 180 degrees to each other
If an atom has three pairs of electrons..
It is trigonal planar, and the atoms are at 120 degrees to each other. However, if there is one lone pair, the molecular geometry is bent, and the angle is slightly less than 120.
If an atom has four pairs of electrons
then the arrangement is tetrahedral. If there is no lone pairs, then molecular geometry is tetrahedral as well and the angles are 109.5. However, with one lone pair, the geometry is trigonal pyramidal, with two lone pairs, it is bent.
If an atom has 5 pairs of electrons
it is trigonal bipyramidal by arrangement. If there are no lone pairs, then the geometry is trigonal bipyramidal as well. If there is one, then it is Seesaw, if there is two, then it is Tshaped, and if there is three, it is linear. The angles are: 90 for axial, and 120 for those between the equatorial atoms.
If an atom has 6 pairs
it is octahedral. All angles are 90. if no lone pairs- octahedral geometry. If one lone pair- square pyramidal. If 2- sqaure planar.
Steps of prediction using VSEPR
1) electron dot formula from molecular formula
2) determine number of electron pairs around central atom
3) determine arrangement
4) getermine geometry.
what affects bond angles and how?
lone pairs- they require more space, therefore, the angles between otehr atoms are less than what predicted
multiple bonds also require more space because they contain greater number of electrons
What is a dipole moment?
it is a quantitative measure of the degree of charge separation in a molecule. measured in debyes. Points from a positive partial charge to negative. Linear, trigonal planar, and tetrahedrtal give 0 dipole.
Valence Bond Theory
attempts to explain the electron pair or covalent bond by quantum mechanics.
1) an orbital of 1 atom comes to occupy a portion of the same region of space as an orbital on the other atom.= overlap
2) no more than 2e per orbital.
orbitals bond in the direction in which they protrude, or point.
Hyprid orbitals.
orbitals used to explain bonding=> take combinations of other orbitals. Number of hybrid orbitals formed = number of orbitals used.
To obtain a bonding description:
1) lewis electron dot
2) use VSEPR
3)# of hybrid orbitals.
4)assign valence electrons to hybridized orbitals
5) overlap orbitals
Multiple Bonding
one hybrid orbital needed for multiple bonds and lone pairs as well.
sigma and pi bonds
sigma vs. pi
sigma- cylindrical shape about axis- formed when two s orbitals, or s and p overlap. along axis
PI- distribution above and below axis. formed by sideways overlap of 2 p orbitals.
double bonds
one pi, one sigma. one unhybridized 2p
triple bond
one sigma, tWO pi. two unhybridized 2P's
Molecular Theory
electrons put into orbitals with least energy.
binding vs. antibonding
bonding
where electrons are concentrated
antibonding
where electrons spend less time.
order of molecular orbitals
see book.
Bond Order
.5(#e bonding-#e antibonding)
diamagnetic vs. paramagnetic
dia- substance not attracted by magnetic field- only paired e
para- slightly attracted
Energy involved in Ionic bonding
can be described by Coulomb's law.
E= kQQ/r
lattice energy
cahnge in energy wen idonic solid spearates into isolated ions.
Main-group ions
losing electrons requires more energy-> IIIA elements show less tendency to form ionic compuonds.
Ionic radius
decreases in period, increases in group. if isoelectronic, go by proton #
Bond Length
distance between nucleus and point of minimum energy
Coordinate covalent bond
wehre both electrosn are donated by one atom:
NH3+
Polar Covalent Bonds and electronegativity
Measure of how able the atom is to draw bonding electrons to itself. I.E-E.A/2
Electronegativity increases in period, decreases in group.
Which Atoms Central?
the one that is least electronegative?
Oxoacids
substances in which O atoms are bonded to a central atom, with one or more H atoms usally bonded to O.
PS. Metals forms basis, Nonmentals form Acids.
Exceptions to the OCtet rule
atoms that have d orbitals
1)calculate total # of e for molecule
2)write skeleton structure
3)distribute electorns to the atoms surrounding the central
4)distribute the remaining electrons as pairs to the central atom. If there are fewer than 8 electrons, suggests that multiple bond is present.
Formal charge
addition equals charge on the molecule
Building up principle
do the triangle all the way up to f
Periodic law
when elements are arranged according to atomic number, physical and chemical properties vary perioducally
effective nuclear charge
positive charge electron experiences from nucleus.
Ionization energy
minimum energy needed to remove the highest energy electron from enutral atom. increases with increasing atomic number. It is harder to remove electrons if one must break the noble gas core.
Electron Affinity
energy change for the process of adding an electron to a neutral atom in the gaseous state to form a negative ion. If large, then the neutral atom is stable. increases in period
Basic Oxide
an oxide that reacts with acids- metals
Acidic Oxide
oxide that reacts with bases- nonmetals
Speed of light
3*10^8m/s. c=v(frequency)* lambda
PLank's Quantization of Energy
E=h*frequency
Energy of a photon
Bohr
E=-Rh/n^2- energy at a principle quantum number
hv=-deltaE=-(Ef-Ei)
hv=Rh(1/nf^2-1/ni^2)
de BroLIE
wawelength(lambda)=h/mv
Uncertainty Principle
(delta x)(delta p)>= h/4pi
uncertainty in position
p=momentum=mv- can interchange
quantum numbers
n=principal energy level
l=angular momentum- 0,1,2,3. n-1
ml=magnetic Q#- from -to+l
ms=spin. +/- 1/2
Ionization energy
increases from first ionization energy to second, etc.. getting closer to nucleus
Electrolyte
dissolves in water- a strong one exists in solution almost entirely as ion. a weak one- doesnt dissolve readily.
Nonelectrolyte
doesnt dissolve readily
Solubility rules.
group IA and ammonium are soluble
Acetates and nitrates are soluble
Most chlorides, bromides, and iodides anre soluble. excepts those with Ag, Hg, and Pb.
Most sulfates are soluble- except Ca, Sr, and Ba, and Ag, Hg, Pb
Most carbonates are insoluble. except group IA and ammonium
Most Phosphates, except IA and nh4+
MOst sulfides are insuluble, except as above
most hydroxides are insoluble, except for above, Ax, Sr, Ba
Types of chemical reactions
precipitation, acid base, oxidation reduction
Acid
species that donates a proton (H+) to another species.
Base
one that accepts proton
Strong Acids
HCLO4
H2SO4
HI
Hbr
HCl
HNO3
Strong Base
LiOH
NaOH
KOH
Ca(OH)2
Sr(OH)2
Ba(OH)2
prefixes 1-10
mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca.
Acid naming
if ate-ic
if ite-ous
Carbonate Ion
CO3(2-),
Nitrite
NO2-
Nitrate
NO3-
Phostate
PO4(3-)
Sulfite
SO3, 2-
Sufate
SO4, 2-
Hypochlorite
ClO-
Chlorite
ClO2-
Chlorate
ClO3-
Perchlorate
ClO4-
Ammonium
NH4+
Cyanide
CN-
Carbonate
CO3,2-
Bicarbonate
HCO3,-
Acetate
C2H3O2, 2-
Oxalate
C2O4,2-
Chromate
CrO4,2-
Dichromate
Cr2O7, 2-
Permanganate
MnO4-