SSI - acids/bases Flashcards
(13 cards)
what is hard and soft acid-base theory?
a theory explaining patterns in lewis base reactivity - hard acids react with hard bases and same for soft, this forms most stable complexes
lewis acid definition
a lone pair acceptor
lewis base definition
a long pair donor
polarisability definition
the ease at which a substances electron cloud may be distorted by a magnetic field
how does polarisability relate to hard/soft acids/bases?
hard species = low polarisability
soft species = high polarisability
what are the physical properties of atoms with high polarisability?
means electrons are only held loosely by nucleus
- atoms have larger ionic radii so electrons are further from nucleus
- atoms also usually have lower charge/O.S. so electrons are weakly attracted by nucleus
- overall low charge density
what are the physical properties of atoms with low polarisability?
means electrons are held tightly by nucleus
- atoms have smaller ionic radii so electrons are closer to nucleus
- atoms also usually have higher charge/O.S. so electrons are strongly attracted by nucleus
- overall high charge density
where are soft metal cations found?
low charge density + large ionic radii so these are usually from lower rows on periodic table
where are hard metal cations found?
high charge density + smaller ionic radii so these are usually from higher rows
where are soft ligands found?
high atomic radii, usually found towards bottom left of p-block
where are hard ligands found?
small atomic radii, usually found towards top right of p-block
what kinds of bonds are formed between hard metal cations + hard ligands?
bonds have more ionic character
what kinds of bonds are formed between soft metal cations + soft ligands?
bonds have more covalent character
