bonding and intermolecular forces Flashcards
formal charge formula and rule
FC = valence elections - 1/2B - L
B = bonding electrons L = number of lone paired electrons
the better formal charge minimizes magnitude of charges
resonance structures
where nonbonding electrons, and double/triple bonds may move around
bond dissociation energy
energy required to break a bond homolytically
homolytic vs heterolytic bond cleavage
homolytic - one electron of the bond being broken goes to each fragment of the molecule, forming two radicals
heterolytic - both electrons of the electron pair that make up the bond end up in the sam atom, forming both a cation and an anion
how does bond order (number of bonds) correlate to bond length and strength
more bonds = shorter bonds and higher bond strength
how does s and p character affect bond length
greater s percentage causes a shorter bond
covalent bonds
formed between atoms when each contributes one or more of its unpaired valence electrons
polar vs non polar
polar - uneven electron density
non polar - even electron density
Lewis base
electron donator, ligand, and nucleophile
Lewis acid
electron acceptor
ionic bonds
when an atom gives its valence electron to another atom to form a cation and an anion
types of molecular geometry if zero lone pairs present
linear, trigonal pyramidal, tetrahedral
types of molecular geometry if one lone pair present
bent, trigonal pyramid
types of molecular geometry if two lone pairs present
bent
number of electron groups and hybridization
2 electron groups = sp
3 electron groups = sp2
4 electron groups = sp3
sigma and pi bonds
sigma - consists of two electrons localized between two nuclei, formed by end to end overlap of one hybridized orbital) (ex. a bond between CH in ethane is sp3-s)
pi bond - formed by the proper parallel side to side alignment of two unhybridized p orbitals on adjacent atoms
what types of bonds in a single, double, and triple bond
single - 1 sigma
double - 1 sigma, 1 pi
triple - 1 sigma 2 pi
What causes a molecular to be non polar
a molecule containing two or more symmetrically oriented polar bonds, canceling out the bond dipoles
types of IMFs
ion-dipole, dipole-dipole, dipole induced dipole, LDF, hydrogen bonding (strongest type)
result of strong intermolecular forcers
greater melting point, greater boiling point, greater visocities, and lower vapor pressures
hydrogen bonding requirements
- a molecule must have a covalent bond between H and either N,O or F
- another molecule must have a lone pair of electrons on an N, O, or F atom
vapor pressure
pressure exerted by the gaseous phase of a liquid that evaporated from the exposed surface of the liquid, increases with weaker IMFs and temperature
types of solids
ionic (strong), network (covalent bonds, strong), metallic (strong), molecular (weak)
