GChem: Bonding and Intermolecular Forces and Thermodynamics Flashcards
The more S character the _____ shorter/longer the bond
The shorter the bond (stronger the bond)
BUT only when comparing the same types of bonds (ex. compare C-O bonds to each other)
Coordinate covalent bond and body example
B/w atoms with lone pair and e- deficient species (lewis acid/electrophile)
Lewis acids: B, (transition) metal cation, BF3 = lewis acid b/c wanted a complete octet
When one atom donates BOTH of the shared e- in the bond
Between lewis base/ligand/nuecleophile and lewis acid/electrophile
A lewis base is a molecule or ion that donates a pair of nonbonding electrons so it must have them in the first place
Ex. In hemoglobin, ligand chelate and O2 binds Fe2+
BH4- CANNOT behave like lewis base
Ionic bonds - the strength of the bond is proportional to… and decrease as ions get closer/farther apart
The strength of the bond is proportional to the charges of the ions and decrease as ions get farther apart
Ex. MgS vs NaCl
MgS - Mg2+ S2-
NaCl - Na1- Cl1-
so MgS “bond” expected to be four times stronger than NaCl bond
Orbital geometry/molecular geometry (state bond angle for each) vs shape of molecule
Orbital geometry/molecular geometry = linear (180º), trigonal planar (120º), or tetrahedral (109.5º)
Shape: bent, trigonal pyramidal
How many sigma and pi bonds are in a triple bond?
one sigma, two pi
List the strengths of IMFs - there are 5
H-bonds Ion-dipole dipole-dipole dipole -induced dipole london dispersion
For IMFs, a _____ more/less polar molecule generates a stronger force and a molecule with ______ more/less e- and ____ larger/smaller size generates a stronger force bc it’s _____ more/less polarized
Pretty sure the polarized rule works for all IMFs
more
more
larger
more
Ex. F2 and Cl2 exist as gases and but Br2 is liquid and I2 is solid bc strength of dispersion forces increase as atomic size increases.
In order to have a hydrogen bonding, you need…
Bond between H and N,O, or F and another molecule must have a lone pair of e-s on an N,O, or F atom.
Ex. water to other waters
Substances with stronger IMF have: \_\_\_\_bp \_\_\_\_mp \_\_\_\_viscosities \_\_\_\_vapor pressure
greater bp and mp
greater viscosity
lower vapor pressure (more easily it evaporates and liquids with high vapor pressures are volatile)
*Ionic Solids
What 2 factors influence its strength?
Electrostatic attraction between cations and anions in a lattice structure (most solid at room temp)
The intermolecular bonds are the same as the intramolecular bonds! All ionic
Magnitude of ion charges (biggest effect)
Size (the smaller the ions, the more attracted to each other)
(I skipped)
Network Solids
Connected in lattice of covalent bonds - super strong
tend to be hard solids at room temp
Ex. diamond and quartz
Metallic solids
conduction electrons
A sample of metal can be thought of as a covalently bound lattice of nuclei and their inner shell electrons surrounded by sea/cloud of electrons Freely moving electrons called conduction electrons
SO EXCELLENT CONDUCTORS OF ELECTRICITY, MALLEABLE, DUCTILE
Almost all solid at room temp
vary in strength
I skipped
Molecular solids
Particles at the lattice points of crystals of molecular solid are molecules held together by one of three types of intermolecular interactions - hydrogen bonds, dipole-dipole forces, or london dispersion so typically has lower mp and bp
often liquids and gases at room temp and start to be more solid as strength of their intermolecular forces increase
Rank the following from highest to lowest bp: I H2SO4 II NH3 III CO2 IV H20
I>IV>II>III
II>I>IV>III
I>III>IV>II
IV>III>I>II
A is the answer
I and IV are liquids at room temp and II and III are already gases!
H2SO4 and H20 have hydrogen bonding but H2SO4 is larger (can have greater polarity) and more sites to accept H-bonds from surrounding molecules
When energy flows into a system from the surroundings, the energy of the system _____ increases/decreases and the energy of the surroundings ____increases/decreases
increases
decreases