Inorganic Chemistry ACS Study Guide

Zeff increases

across the periodic table left to right

Ionization energy increases

left to right across a row and up column of the periodic table

Electron affinity increases

left to right across a row and up a column of the periodic table

Element size increases

right to left across and row and down a column of the periodic table

Ionization energy

the energy required to remove an electron from an atom

Electron affinity

the energy required to add an electron to an atom

In M.O. theory, the number of atomic orbitals must equal...

the number of molecular orbitals

M.O. requirements

1. M.O.s must be built from symmetrically appropriate orbitals

2. Energy in bond pairs needs to be approximately the same

3. Efficient overlap of orbitals in a bond

Anti bonding orbitals

higher in energy than bonding orbitals, created by overlap of orbitals that are out of phase with each other, contain nodes

Node

a region with no electron density

Bond order

b=0.5(# bonding electrons - # anti-bonding electrons)

tells you how many bonds to expect in a molecule

M.O.s for B2, C2, and N2

there is a small change in energy between 2s and 2p orbitals, causing them to mix

this results in the 3 sigma orbital to be higher in energy than the 1 pi orbital

Heteronuclear M.O. theory

the more electronegative atom is lower in energy

Non-bonding orbitals

essentially lone pairs, caused when the overlap between orbitals is not enough

CO M.O. diagram

reaction takes place at carbon because the frontier orbital is mainly "carbon-like" in character

the 3 sigma orbital switches places with the 1 pi orbital

"X-like character" in M.O.

an orbital has "x-like character" when it is much closer in energy to one atom rather than the other

Symmetry element

a point or an axis that a symmetry operation exits, such as a rotation, mirror plane, inversion, etc.

Symmetry operation

perform a transformation that leaves the "new" version of the molecule identical to the original

Rotation, Cn

rotation=360/n

Identity, E

if you spin a molecule 360 degrees, you'll end up with exactly what you started with, every molecule has this symmetry operation

Mirror plane, sigma h

reflecting a molecule through a plane of symmetry

Inversion center, i

reflects all points of a molecule through the center

Improper rotation, Sn

1. rotate by 360/n

2. reflect through a perpendicular mirror plane

Point group

contains all symmetry elements of a molecule or atom

Point group of PtCl4

D4h

Point group of water

C2v

Point group of NaOH

Cinfinityv

Molecule with C1 point group

a chiral molecule

Point group of ethane (CH4)

Td

Mulliken symbols

A ,B: nondegenerate

E: doubly degenerate

T: triply degenerate

Linear molecule vibrational degrees of freedom

3n-5, n = # of atoms

Non-linear molecule vibrational degrees of freedom

3n-6, n = # of atoms

Point group of BH3

D3h

Point group of NH3

C3v

Walsh diagram

tells us about the quality of orbital overlap as we change from one geometry to another

Arrhenius definition of acids and bases

acid: increases [H+] in water

base: increases [OH-]/decreases [H+] in water

Bronsted-Lowry definition of acids and bases

acid: H+ donor

base: H+ acceptor

(conjugate acids and bases)

Lewis definition of acids and bases

acid: lone pair acceptor

base: lone pair donor

An acid-base interaction is...

an interaction between the filled HOMO of a base and the empty LUMO of an acid

Solvent leveling effect

you cannot have an acid that is more acidic than the characteristic cation of that solvent.

ex) the strongest acid we can get in water is H3O+

Oxyacids

acids with oxygen present, (O)pA(OH)q

Predict the pKa of an oxyacid

(O)pA(OH)q

pKa=8-5p

with electronegativity, pKa=10.5-5p-Xa

Monodentate ligand

a ligand capable of forming one bond with a metal

Bidentate ligand

a ligand capable of forming 2 bonds with a metal, must bind in cis fashion

Tridentate ligand

a ligand capable of forming 3 bonds with a metal

Porphyrin

hemoglobin is an example

Stability constant (binding constant) BMLH

mM + lL + hH+ <---> [MmLlHh]

M: metal

L: ligand

H: H+ concentration

MA4B2 has 2 isomers

cis and trans

MA3B3 has 2 isomers

fac and mer

5 d orbitals

dz2

dx2-y2

dxz

dyz

dxy

Crystal field theory (CFT)

d orbitals split in energy based on their symmetry

Delta o

the energy between the split orbitals in a crystal field

Barycenter

the center of the split d orbitals in crystal field theory

High spin metal

relatively small delta o because of weak field metals

Low spin metal

relatively large delta o because of strong field metal

Tetrahedral metal complexes

most are high spin, energy level splitting switches

Metal orbitals that are available for bonding

(n-1)d : eg and t2g symmetry

ns : a1g

np : t1u

Pi-donors

ligand donates pi electrons to metal

Pi-backbonding

ligands accept electrons from the metal into their pi* orbital which is the LUMO

IR spectroscopy of backbonding

backbonding can be seen in IR by a shift from a triple bond to a double bond

Jahn-Teller distortion

a molecule will distort to remove artificial degeneracy

ex) elongation/contraction

Vibronic coupling

changes orbital mixing, breaks grade/ungrade designations

Spin-orbit coupling

the interaction between a particle's spin and its orbital angular momentum

d-d transitions cause us to see color

different compounds have different colors because of differences in delta 0

LMCT (ligand to metal charge transfer)

L is oxidized, M is reduced

MLCT (metal to ligand charge transfer)

M is oxidized, L is reduced

Organometallics

carbon-based molecules interacting with metals

Pi-accepting properties

as the ligand becomes more alkyl-like it becomes less pi-bonding and more sigma-bonding

Cone angle

large R group = large cone angle

small cone angles allow for more coordination sites

Substitutional alloy

remove some atoms and substitute them with an element that likes to make the same amount of bonds, done to make stronger materials

Interstitial alloy

a small element fills in the holes between metal atoms and makes a stronger material

Born-Haber cycle

1. prepare the elements to form ions by breaking bonds

2. form ions

3. allow them to come together to make the molecule

ex) NaCl

n-type semiconductors

add electrons to conductive orbitals

p-type semiconductors

remove electrons from valence orbitals

Semiconductors

determined by band gaps

Disproportionation

ex) 2Mn(III) ---> Mn(IV) + Mn(II)

Latimer diagram

shows the reduction potentials connecting a series of species containing an element in different oxidation states.

goes from most oxidized to least oxidized

Calculating reduction potential

E^o = (V1E1+V2E2)/(V1+V2)

Difference between an allotrope and an isotrope

allotropes differ in the arrangement of atoms for the element

isotopes differ in the number of neutrons in the nucleus

The de Broglie relationship

lambda=h/mv and quantifies the amount of wave character possessed by a moving mass.

the wave character for a moving particle will only be significant if the wavelength of the particle is on the order of the size of the particle or the size of the system of which the particle is part

Heisenberg uncertainty principle

it is impossible to know exactly both the velocity and the position of a particle at the same time

n

principal quantum number, determines size/energy of the orbital

l

orbital quantum number, determines the 3D shape of the orbital

ml

magnetic quantum number, determines the orientation of an orbital with respect to Cartesian axes

ms

spin quantum number, determines electron orientation with respect to an external magnetic field

Penetration in atomic orbitals

orbitals of higher energy may overlap close to the nucleus with orbitals having lower energy, it allows the electrons to be closer to the nucleus and experience greater nuclear charge and less shielding from other electrons, s-orbitals are the most penetrating followed by p and then d

Zeff definition

the effective nuclear charge is the actual charge reduced by the amount of shielding that an electron feels from other electrons in the system

Aufbau principle

it states that atomic energy levels will be filled starting with the lowest energy levels first and filled to result in the lowest energy configuration when possible

Pauli exclusion principle

it states that no two electrons in the same atom can have the same set of 4 quantum numbers

Hard acid

small and very positively charged cations

ex) Al3+, Zn2+

Hard bases

small and very negatively charged anions

ex) F-, Cl-

Soft acid

low charge density and large size, usually transitions metals

ex) Au, Ag, Hg

Soft base

low charge density and large size, usually carbon and sulfur based ligands

ex) I-, H-, CN-, CO, SCN-, R3P

Hard-hard combinations

mostly ionic in character, favorable

Soft-soft combinations

mostly covalent in character, favorable

The acidity of oxyacids increases as the electronegativity of the central atom increases

this is due to the fact that the central atom draws electron density from the O atom, making the OH bond become more polarized and more likely to be ionized

The acidity of oxyacids increases as the number of oxygem atoms attached to the central atoms becomes larger

this is due to the fact that each O added reduces the electron density of the central atom, making any OH bonds more polarized and likely to be ionized

CSFE

=-(# electrons in lower state x 0.4)delta o + (# electrons in upper state x 0.6) + # pairs of electrons total

Common features of oxidative addition

1. cleavage of x-y bond

2. metal oxidation state increases by 2

3. metal coordination increases by 2

Common features of reductive elimination

1. formation of x-y bond

2. metal oxidation state decreases by 2

3. typically 16 electron products