Hybridization And Thermodynamics Flashcards
valence bond theory resilts from what
the pairing of unpaired electrons in aromic orbitals
single bond
sigma bond
double bond
sigma bond and pi bond
triple bond
sigma bond and 2 pi bonds
cannot hybridize
terminal hydrogen or the halides
electron promotion does not occur with nitrogen because
promotion would not increase the number of unpaired availabke for bonding
pi bonds are
unhybridized px or py orbitals
to determine the hybridization of an atom
of bonded atoms + # of lone pairs
thermodynamics
deals with the energy change and sponteneity associated with a chemical reaction
ΔHb (and charge)
▪bond enthalpy: it takes energy to break a bond
▪always pos
ΔHr
enthalpy
negative ΔHr
▪exothermic reaction
▪bonds stronger in products than reactants
positive ΔHr
▪endothermic reaction
▪bonds stronger in reactants than products
ΔHf
heat of formation
when does ΔHf=ΔHr
when forming 1 mol of compounds from pure elements in their most stable form at standard state
the sign of ΔG for a spontaneous reaction
negative
Hess’s Law
if 2 or more chemical equations are added to give another equation, their corresponding ΔHr must be added
spontaneous change
a process that, given enough time, occurs without the need for outside intervention
entropy (s)
a measure of the disorder of a system
ΔS is pos
imcrease in disorder
ΔS neg
decrease in disorder
increase in disorder =
increase in chance that a reaction is spontaneous
standard temp
298K
ΔGf measures
▪free energy of formation
▪a compunds stability relative to its elements
ΔGf < 0
compound is thermodynamically stable relative to its elements
ΔGf > 0
compound is thermodynamically unstable relative to its elements
when ΔH is - and ΔS is +
spontaneous at all T
ΔH + and ΔS -
nonspontaneous at all T
ΔH + and ΔS +
spontaneous at high T and nonspontaneous at low T
ΔH - and ΔS -
spontaneous at low T, nonspontaneous at high T
