CH3.3 Chemistry of the p-block Flashcards
how many oxidation states do elements in the p block normally have and why this amount
2 becuase one of them equals the group number and one is is two less then that.
iner pair effect
The tendancy of S2 pairs of electrons in an atom to stay paired leading to a lower oxidation state
octet expansion
The ability of some atoms to use d-oribtals to have more than eight electrons in their valence shell.
trend of stability of oxidation states in the p block
stability of lower oxidation states become greater down the group.
name for , tendency of heavier atoms to form lower oxidation states
inert pair effect
where does the inert pair effect hapen (which groups)
lower elements of group 3,4 and 5
why can elements in period 2 not have more then 8 bonds
period 2 elements do not have accsses to the d-orbitals, so they can not octet exspand meaning there are only eight electrons in the outer shell availbale for bonding.
amphoteric
materials react with both acids and bases
how do we show that something is amphoteric
we react it with a acid and a base
p block elements form amphoteric …..
oxides
when showing that something is amphoteric what are the chemicals we normally react it with
nitric acid or hydrochloric acid
and
sodium hydroxide
equation to show that aluminium oxide is amphoteric
Al2O3 + 6HCL –> 2AlCl3 + 3H2O
AL2O3 + 2NaOH + 3H2O –> 2Na(Al(OH)4)
What happens when sodium hydroxide is added to a solution contatining a amphoteric metal compound.
a precipitate of the metal hydroxide is formed. Since the hydroxide can react with more sodium hydroxide these precipitates will then redissolve.
equation for sodium hydroxide being added to a solution of a amphoteric metal compoud (e.g.Aluminiumoxide)
amphoteric metal compound - Al2O3
Al3+ + OH- –> Al(OH)3
Al(OH)3 + OH- –> (Al(OH)4)- excess sodiumhydroxide
electron deficeitn atom
a atom that does not have a full outer shell of electrons
how many bound do group 3 elements normally form in covalent bonds
3
what type of bonding is common in electron deficient species and why
co-ordinate bonding, because it wants to gain extra electrons pairs
how do electron deficient species form co-cordinate bonds
2 possible ways
they react with outher compounds or by forming dimers.
how do dimers work
each elelctron deficient compound uses a lone pair of electons from another electron deficient species to form coordinate bones.
give a exsample of a dimer
aluminium chloride in gas phase
what type of compound is a dimer classsed as and why
a donar-acceptor compound, because one molecule donates a lone pair and the other accepts it.