Unit 3.3 - P-Block (physics&mathstutor) Flashcards

1
Q

what is amphoteric behaviour

A

a species which can act both as an acid and a base

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2
Q

which 2 p-block elements show amphoteric behaviour

A

Al/Al3+
Pb/Pb2+

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3
Q

lead oxide + hydrochloric acid

A

PbO + 2HCL –> PbCl₂ + H₂O

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4
Q

lead oxide + sodium hydroxide

A

PbO + NaOH + H₂O –> NaPb(OH)₃

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5
Q

What is inert pair effect

A

Tendency of S² electrons to stay paired (remain inert)
and form lower oxidation states

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6
Q

what is inert pair effect used to explain

A

That the increasing stability of the oxidation that are 2 less than group number

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7
Q

how does the stability of oxidation states change down group 3

A

stability of +1 oxidation state increases down group

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8
Q

how does the stability of oxidation states change down group 4

A

stability of +4 oxidation state decreases down the group
stability of +2 oxidation state increases down the group

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9
Q

how does the stability of oxidation states change down group 5

A

stability of +5 oxidation state decreases down group
stability of +3 oxidation state increases down the group

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10
Q

what is the bonding like in Al₂Cl₆ (aluminium hexachloride)

A

-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

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11
Q

what is the bonding like in NH₃BF₃
(ammonia boron trifluoride)

A

-it is a donor-acceptor
-coordinate bond formed between N and B atoms.
-nitrogen supplies both electrons for the covalent bond

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12
Q

describe structure of cubic boron nitrate

A

-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

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13
Q

describe structure of hexagonal boron nitrate

A

-layered structure(like graphite)
-layers form 2D giant covalent network
-alternate boron and nitrogen atoms link = hexagonal rings (thin layers) held by WEAK IMF

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14
Q

why is boron nitrate a good lubricant

A

hexagonal boron nitrate has WEAK IMF ∴ layers can slide

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15
Q

what is the general acid-base behaviour trend of group 4 oxides

A

acidity decreases as you go down group

don’t completely lose acidity(∴amphoteric)

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16
Q

what are the acid-base properties of carbon dioxide

A

top of group 4 ∴ acidic and reacts wiith bases

17
Q

what are the acid-base properties of lead oxide

A

bottom of group 4 ∴ amphoteric, reacts with acids + bases

18
Q

how does CCl₄ react with water

A

does not react

19
Q

how does SiCl₄ react with water

20
Q

how does PbCl₂ react with water

A
  • partially soluble in cold water
  • more soluble in hot water
21
Q

why does CCl₄ tend to not react with water

A

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

22
Q

How is SiCl₄ able to react with water

A

Silicon atom is big ∴ space for oxygen on water to attack silicon atom

23
Q

how does PbCl₂ react with water

A

-has lots of ionic character
-slightly soluble in cold water
-soluble in hot water

24
Q

what is a disproportionation reaction

A

a reaction when a species undergoes oxidation and reduction to form 2 different products

25
why is chlorine used in water treatment
kill bacteria ∴ making water safe (due to oxidising power)
26
how does sodium chloride and sodium fluoride react with conc sulfuric acid
chlorides and fluorides are not oxidised by sulfuric acid
27
how do bromide ions react with conc sulfuric acid
bromide ions can reduce conc sulfuric acid
28
how do iodine ions react with conc sulfuric acid
iodine ions are stronger reducing agents than bromide ions
29