P-Block Flashcards
What is the inert pair effect?
In group 4 the inert pair effect means lighter elements e.g carbon are more stable in a 4+ oxidation state while heavier elements e.g lead are more stable ina 2+ oxidation state. This is why PbO and CO2 are more common than PbO2 and CO
Why is CO a strong reducing agent?
Since the carbon is in the 2+ state and aims to reach the 4+ state it loses electrons easily
Fe2O3 + 3CO -> 2Fe + 3CO2
Why is PbO2 a strong oxidising agent?
The Pb is in the 4+ states and aims to reach the 2+ state so it gains electrons easily
PbO2 + 4HCl -> PbCl2 + Cl2 + 2H2O
Explain why the max covalency for period 2 is 4
No other orbitals are available for electrons
Explain why the max covalency for periods >2 is 4,5 or 6
The d-orbital is available for electrons to move into eg in phosphorous
What is electron deficiency?
Lack of complete valence shell
How can AlCl3 dimerise? (eqn)
2AlCl3 -> Al2Cl6
What is the difference in shape of the two types of aluminium chloride?
AlCl3 - Trigonal planar
Al2Cl6 - tetrahedral
How does ammonia and boron tetrafluoride form a donor acceptor pair?
The nitrogen has a lone pair of electrons to fill the space in the borons valence shell forming a coordinate bond
What is an amphoteric compound?
A compound that can react with acids and bases
How can lead and hydroxide be amphoteric?
Pb2+ (aq) + 2OH- (aq) -> Pb(OH)2(s)
This can be reversed with the addition of an acid
What is meant by isoelectronic?
Molecules that have the same electron configuration
Why can’t H-BN conduct heat like graphite?
Both molecules contain a spare p-orbital however H-BN spare p-orbital doesn’t have any free electrons to carry charge while graphite does
How is C-BN similar to diamond?
Both have lattice structures with strong electrostatic forces between them hence why they are very solid
What is C-BN used for?
C-BN is used for coating on cutting equipment and on bullet coatings due to its strength
What is H-BN used for?
H-BN is used as a lubricant due to its weak layers
How is H-BN similar to graphite?
Both have layers of hexagonal molecules with weak VDW forces between them
Describe CCl4 and its reaction with water
- Tetrahedral structure
- colourless liquid
- immiscible with water so it doesn’t react
Describe SiCl4 and its reaction with water
- Tetrahedral
- colourless liquid
- white fumes
- reacts vigorously to form SiO2
Describe PbCl2 and its reaction with water
- White insoluble solid
- Dissolves to produce tetrachlorolead ion and HCl
What is a disproportionation reaction?
A reaction where an element is both reduced and oxidised at the same time
Reaction of chlorine with Cold dilute OH- and its effect on oxidation number
Cl2 + 2OH- -> Cl- + ClO- + H2O
(-1) (+1)
Reaction of chlorine with warm conc. OH- and its effect on oxidation number
Cl2 + 6OH- -> 5Cl- + ClO3- + 3H2O
(-1). (+5)
Describe how NaCl reacts with water
misty white fumes (HCl)
Describe how NaBr reacts with H2SO4
misty white fumes (HBr) brown fumes (Br2) choking gas (SO2)
Describe how NaI reacts with water
misty white fumes (HI)
purple fumes (I2)
choking gas (SO2)
Rotten egg smell (S)
