Unit 3.3 - P-Block (physics&mathstutor) Flashcards
what is amphoteric behaviour
a species which can act both as an acid and a base
which 2 p-block elements show amphoteric behaviour
Al/Al3+
Pb/Pb2+
lead oxide + hydrochloric acid
PbO + 2HCL –> PbCl₂ + H₂O
lead oxide + sodium hydroxide
PbO + NaOH + H₂O –> NaPb(OH)₃
What is inert pair effect
Tendency of S² electrons to stay paired (remain inert)
and form lower oxidation states
what is inert pair effect used to explain
That the increasing stability of the oxidation that are 2 less than group number
how does the stability of oxidation states change down group 3
stability of +1 oxidation state increases down group
how does the stability of oxidation states change down group 4
stability of +4 oxidation state decreases down the group
stability of +2 oxidation state increases down the group
how does the stability of oxidation states change down group 5
stability of +5 oxidation state decreases down group
stability of +3 oxidation state increases down the group
what is the bonding like in Al₂Cl₆ (aluminium hexachloride)
-It is a donor-acceptor dimer.
-Made of 2 separate identical molecules which are linked by 2 coordinate bonds
-2 chlorine atoms share their lone pair of electrons with 2 atoms of aluminium = coordinate bonds
what is the bonding like in NH₃BF₃
(ammonia boron trifluoride)
-it is a donor-acceptor
-coordinate bond formed between N and B atoms.
-nitrogen supplies both electrons for the covalent bond
describe structure of cubic boron nitrate
-alternately linked boron and nitrogen atoms
-structure is a tetrahedral bond network(like C in diamond)
-lone pair of electrons on N are accepted by B = giant 3D covalent lattice
describe structure of hexagonal boron nitrate
-layered structure(like graphite)
-layers form 2D giant covalent network
-alternate boron and nitrogen atoms link = hexagonal rings (thin layers) held by WEAK IMF
why is boron nitrate a good lubricant
hexagonal boron nitrate has WEAK IMF ∴ layers can slide
what is the general acid-base behaviour trend of group 4 oxides
acidity decreases as you go down group
don’t completely lose acidity(∴amphoteric)
what are the acid-base properties of carbon dioxide
top of group 4 ∴ acidic and reacts wiith bases
what are the acid-base properties of lead oxide
bottom of group 4 ∴ amphoteric, reacts with acids + bases
how does CCl₄ react with water
does not react
how does SiCl₄ react with water
violently
how does PbCl₂ react with water
- partially soluble in cold water
- more soluble in hot water
why does CCl₄ tend to not react with water
for reaction, oxygen’s lone pair from water must bond to carbon atom in CCl₄
-chlorine=bulky, carbon atom is small ∴ hard for oxygen to get near carbon atom
- lots of repulsion between lone pairs as oxygen gets close to chlorine ∴ unstable
How is SiCl₄ able to react with water
Silicon atom is big ∴ space for oxygen on water to attack silicon atom
how does PbCl₂ react with water
-has lots of ionic character
-slightly soluble in cold water
-soluble in hot water
what is a disproportionation reaction
a reaction when a species undergoes oxidation and reduction to form 2 different products
why is chlorine used in water treatment
kill bacteria ∴ making water safe
(due to oxidising power)
how does sodium chloride and sodium fluoride react with conc sulfuric acid
chlorides and fluorides are not oxidised by sulfuric acid
how do bromide ions react with conc sulfuric acid
bromide ions can reduce conc sulfuric acid
how do iodine ions react with conc sulfuric acid
iodine ions are stronger reducing agents than bromide ions
