N330 Terms Midterm 2
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- bronsted acid
- a proton donor
- Bronsted base
- a proton acceptor
- 4 things that dictate coordination number
- 1. size of central atom 2. steric interactions between ligands 3. electronic interations - # of d electrons on metal, and if ligand can form multiple bonds 4. Charge - low valence = low coordination #
- electrophile
- electron pair acceptor AKA lewis acid!!!
- Neucleophiles
- ligands AKA lewis bases!!!
- strong base
- - virtually fully protonated in water -Example is the oxide ion (O2-) which is immediately converted to OH- ions in water.
- polyprotic acid
- a substance that can donate more than one proton. (H2S for example) in 2 successive proton donations it becomes S2- In these two deprotonations, the second Ka is always smaller than the first. This is becasue the proton becomes increasing harder to remove
- Basicity Constant
- Kb - if Kb is alot less than 1, then only a small fraction of B molecules are protonated, therefor, the base is a weak proton acceptor and its CA is present in low concentrations.
- Acidity Constant
- If Ka is alot less than 1, then the proton retention is favored by the acid.
- Autoprotolysis constant
- The constant involved when the proton transfer from one water molecule to another occurs.
- 3 classes of bronsted acids
- aqua acids hydroxoacids oxoacids
- aqua acids
- an acid in which the acidic proton is on a water molecule coordinated to a central metal ion.
- hydroxoacid
- an acid in which the acidic proton is on a hydroxyl group without a neighbouring oxo group (=O)
- Oxoacid
- an acid in which the acidic proton is on a hydroxyl group with an oxo group attached to the same atom.
- Periodic trend of aqua acid strength
- increase with increasing positive charge of the central metal ion and with decreasing ionic radius
- equation for determining pka of oxoacids
- pka = 8-5p (p= # of oxo groups)
- Conjugate base
- a species with one or fewer protons than its parent acid
- Conjugate acid
- a species with one or more protons that its parent base
- paulings rule
- 1) for oxoacid pka = 8-5p (OpE(OH)q) 2)The successive pka values of polyprotic acids (those with q>1), increase by 5 units for each proton transfer
- amphoteric oxide
- is an oxide that reacts with both acids and bases.
- oxidation state for amphoteric Sc:
- none, basic at 3+ and that is all
- oxidation state for amphoteric Ti
- 4+, nothing higher (Acidic)
- oxidation state for amphoteric V
- 4+
- oxidation state for amphoteric Cr:
- 4+
- oxidation state for amphoteric Mn
- 4+
- oxidation state for amphoteric Fe:
- 3+ and 4+
- oxidation state for amphoteric Co
- 3+
- oxidation state for amphoteric Ni
- 3+
- oxidation state for amphoteric Cu
- 2+
- oxidation state for amphoteric Zn
- 2+
- elements that have amphoteric oxides in all oxidation states
- Be, Al, Ga, Ge, In, Sn, Pb
- Elements that have acidic oxides in high ox states and basic oxides in low ox states
- As, Sb, Bi
- Lewis acid
- electron pair acceptor
- Lewis Base
- electron pair donor
- 4 possibilities with lewis acids
- 1)incomplete octet can accept electron pair 2)metal cations bind ligands with lone pairs 3)complete octet rearranges to react with lone pair 4)molecule can accept electron pair to expand octet
- ligand
- an ion or molecule that can have an independent existence
- A complex is:
- a combination of a lewis acid (the central metal atom) with a number of lewis bases (ligands) bound.
- Tetrahedral (coordination #)
- 4 - tetraheral complexes are favored over higher numbers when the central atom is small or the ligands are big because then the ligand-ligand repulsions override the energy advantage of forming more metal-ligand bonds.
- square planar (coordination)
- 4 - are typically observed for metals with 8 d electrons.
- common structure of 5-coordination complexes
- square pyramidal and trigonal bipyramidal
- common 6-coordination
- octahedral
- 2-coordination complexes are common in:
- groups 11 & 12 - typical for bottom right part of transition metals
- Which 4-coordination complex has possible isomers and what are they?
- square planar & cis and trans cis - like ligands are next to eachother trans - like ligands are opposite.
- ambidentate ligands
- ligands that have more than one different potential donor atom (ex. -NCS and -SCN)
- chelate
- a complex in which a ligand forms a ring that includes the metal atom. Binds to metal at two separate sites with 2 separate lone pairs.
- chiral compound
- non-superimposible on its mirror image.