chem

EN difference for pure/nonpolar covalent bonds

< 0.4

EN difference for polar covalent bonds

0.4-1.9

EN difference for ionic bonds

>1.9

Which atoms MUST obey the octet rule

C, N, O, F

Most ___ anions have resonance structures

polyatomic

Bond order

the number of electron pairs being shared by a given pair of atoms

Average bond order

# of bonds/ # of elements around central atom

Exceptions to the octet rule

H = 1 e- pair

Be = 2 e- pair

Boron/Al = 3 e- pait

Expanded valence shell possible for nonmetals from period 3 or higher (d orbitals) if central atom

bond dissociation energy (homolysis)

approx. energy required to break 1 mol of bonds in gas phase

AX2

linear, 180°

AX3

trigonal planar, 120°

AX2E

bent, nonideal

AX4

tetrahedral, 109.5°

AX3E

trigonal pyramidal, nonideal

AX2E2

bent, nonideal

AX5

trigonal bipyramidal; 90, 120

AX4E

seesaw, nonideal

AX3E2

T-shaped, nonideal

AX2E3

linear, 180°

AX6

octahedral; 90°, 180°

AX5E

square pyramidal; nonideal

AX4E2

square planar; 90°

Strong Acids

HCL = hydrochloric acid
HBr = hydrobromic acid
HI = hydroionic acid

HClO3 = chloric acid
HClO4 = perchloric acid
HNO3 = nitric acid
H2SO4 (not really though since only first ionization strong) = sulphuric acid

Strong Bases

Grp 1 and 2(sml amt fully ionized) hydroxides --> NaOH

- Grp 1 and 2 hydrides (H-) --> NaH

- Grp 1 and 2 oxides (O^2-) --> NaO2

Ionic bond (e-sharing, e- transfer, between what)

yes e share and transfer, metal + nonmetal

covalent bond (e-sharing, e- transfer, between what)

yes e sharing, no e transfer, bw 2 non metals

formal charge on each atom

FC = #ve- (ptable) - (0.5)(#boding e-) - #nonbonding/lone pair e-

how to minimize FC

create multiple bonds. this is usually when neighbouring atoms hv opposite charges

Resonance hybrid

molecules exist as hybrid of all formal resonance structures 

Average formal charge for atom in molecule

total charges on atom/total # of that atom

Bond order

single → double → triples

covalent bond length

approx distance bw 2 nuclei w/in C-bond

Bond dissociation energy (homolysis)

approx E needed 2 break 1 mol of bonds in gas phase (sometimes 1 bond or 1 mol of bonds if more than 1 bond)

bond order and bond length relationship

increase bond order = decrease bond length

+ve → -ve extreme on electrostatic potential maps

ionic, polar covalent, pure/nonpolar covalent

what do electrostatic potential maps show

the effect of EN on charge distribution

if mol is charged, which atom is most and least EN

-ve FC = most EN atom, +ve FC = least EN atom

what do electrons apart from C, N, O, F prioritize: octet rule or minimizing FC

minimizing FC

repulsion bw bond pairs + lone pairs and bond order

bond pair/bond pair < bond pair/lone pair < lone pair/lone pari

single < double<triple

Electron group in reference to central atom

bond bw A and X + lone pairs (+ atoms)

electron group geometry

atom + bonds, dictate molecular shape, X atom arrangement

biggest/strongest repulsion bw what angle?

90

Water facts (polarity, heat capacity, density, boiling point, dipoles, solute vs solvent, reaction rate, A/B strength)

• good polarity → universal solvent

• high specific heat capacity

• solid < liquid H2O density

• high bp

• dipoles

  • O = -ve dipole

• ion-dipole interxns

  • more E released -. forms hydration shells (dipoles move towards cat/anions and create shells around ion = decrease in potential energy of system

• usually solvent

• rarely rxt w itself

• very weak A/B/electrolyte

electrolyte

ability to make electrical current in H2o

strong electrolyte

soluble salt → all fully charges ion in H2o (fully ionized)

weak electrolyte, Kvalue

partially ionized mol, weakly soluble salts, K < 1

non electrolyte

netral atom w X ions and X current

strength factors of electrolytes 

1) degree of ionization of electrolyte in aq solution ( increase ion charge magnitude = increase electrical current

2) # on ions/mol produced via ionization

cost-benefit analyses needed in terms of pesticides

agriculture/food production +disease prevention vs. long term environmental/health issues (can’t always anticipate health harm of pesticides)

Hydroxyapatite

Ca5(po4)3oh, primary mineral in tooth enamel that support bone growth w/o bd/dissolving. OH- gps reside in channels

importance for OH- in channels

critical for stability

can OH- in channels be replaced w other groups

yes and no, dependant on group as it can affect the strength of hydroxyapatite in enamel. enamel deficiency = enamel bd = cavities

what can remove OH- from channels

reactions w acids (food, plaque, etc). OH- + H+ → H2O = neutralization

what can replace the OH- in channels?

CO3 2-, F-, Cl-

what’s best in replacing OH- channels

F- (from toothpaste) in fluroapatite, keeps tooth enamel and channels strong, less soluble that hydroxyapatite in H20 so less likely to bd (smaller Ksp)

RULES WHEN AQ SOLUTIONS MIXED TGTH

1. see if precipitate is formed → X = no reaction, go to #2

2. MOLECULAR FORMULA: balanced chem eq w states

3. TOTAL IONIC EQ: separate aq molecules into cation + anions

4. NET IONIC EQ: cancel out spectator ions

equilibrium

X macroscopic change in rxn conditions = reached eq

rate of forward run = rate of reverse run

rare for equal [] of R and P @ eq

very small (k<10-4) =

eq mixture contains almost all R, rxn barely proceeds

intermediate 10^-4 < K < 10^4 =

eq mixture contains mix of R + P

very large K>10^4

eq mixture contains almost all P, rxn goes to completion

only call that can change EQ

Temperature

K= [C]^c + [D]^d / [A]^a +[B]^b, X include solids/liquids

K formula

activity ‘a’

effective [] or pressure, assume y=1 under ideal conditions, so a=1 w [] and pressure

K(ow)

octanol-water partition coefficient, X reaction but change in location 

aq(dissolved in water) ←> org (dissolved in octanol)

octonol

organic solvent used to mimic biological environments

what does Kow measure

how hphobic/lipophillic substance is. if K ow< 1 = X stay in body

K ow and body relationship

larger Kow= stay in body longer and partition + bioaccumulate in fat+muscle

measure drug behaviour Kow

log (Kow) predict drug behaviour, >4 = slow metabolism/elimination

POPs

persistent organic pollutants

1. persistent: resist transformations (x biodegrade quick)

2. toxicity: acute (immediate)/chronic toxicity

3. bioaccumulate/biomagnification: []ed in fatty tissues (high Kow), further amplified up the food chain

Le Chatelier’s Principle

eq subjected to stress→ reach new eq to partially affect stress impact

1. decrease volume = increase pressure = favour direction w fewer moles

   1. adding gas/aq sol that can react w system= change in EQ

2. inert gas added = X change in partial pressures involved

3. increase [] R = shift toward P

4. increase temp = shift towards endo rxn( h>0) (heat acts as reactant in a way)

Rxn Quotient

ratio of P to R at any instant, X a constant, can take on any value

Q>K

shift to left/R, more P present

Q<K

shift to right/P, more R present

Q=K

Rxn X shift, already at eq

where does the rxn ALWAYS shift towards

[initial] = 0

what to do if both P and R have [initial]

1. find Q

2. compare Q and K and determine shift

3. plug value from E (ICE) into K expression

if given moles of gas

convert to bars w PV=nRT

common ion effect

common ion is present, molar solubility of slight soluble ionic compound =much lower, less R will dissolve

Qsp>Ksp

rxn shift to R, precipitation should occur, (super)saturated

Qsp<Ksp

rxn shift towards P, precipitation X occur, unsaturated

Qsp=Ksp

rxn X shift, precipitation already occurred, saturated

calculating Qsp after solutions mixed tgth

calculate [] of R after solutions mixed (new V, use C1V1=C2V2

heterogenous eq

aq + g in solution, calculate K using both [] and P

Arrhenius Theory

Acid generate and give H+, base generate and give OH-

protic acids and metal hydroxides in water

Bronsted Lowry

acid= H+ donor and get lone pair in exchange, base= H+ acceptor

Lewis AB

acid accept pair of e-, base donate pair of e-

apply to all types of A and B (aq, non aq, non protic acid

ocean acidification

Co2 in atmosphere absorbed into ocean

Co2 + 2h2o → h3o+ + hco3- (acidic) → ocean = increase acidic

increased acidity destroys seashells and coral reefs (CaCO3(s)) through rxn w CO32- (forced eq of CaCO3 towards forward rxn = bd)

more H+ into organisms = tissue more acidic, which needs a lot of E to remove or need buffer mol

curved/double arrows

show electron flow from -ve to +ve

amphiprotic

act as acid or base, water

generate/accept/donate H+

acid base properties

amphoteric

X need to generate or accept H+ but acts like acid and base

Henry Law

increase amt gas above liquid (ex co2 atmosphere), increase of that gas dissolved in the liquid (increase co2 in ocean)

find [] from ph

10^-ph

find ph from []

-log[]

Ka, Kb >>>1

products dominate, strong AB completely dissociate

Ka, Kb < 1

WA/B partial dissociate, reactants dominate

WA contain

carboxylic acid = -cooh

WB contain

nitrogen (lone pari of e- can accept a proton)

eq/small x approx

[initial]/K > 100

[initial] = [HA]/[B]

percent ionization

[H3O+] eq/[HA]inital x 100%

___Ka/Kb → ___ (more +ve/-ve) pKa/pKb → ___acidic/basic

larger Ka/Kb → smaller (more +ve/-ve) pKa/pKb → more acidic/basic

Ka+CB Kb = 10^14