5.3.1 Transition Elements Flashcards

1
Q

transition element

A

d block elements that form at least one ion with a partially filled d-orbital

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2
Q

in terms of electron configuration, what are the 2 exceptions?

A

chromium - half filled d sub-shell
copper - fully filled d sub-shell
for additional stability

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3
Q

why aren’t zinc and scandium transition elements?

A

Sc forms Sc³⁺, and has an empty d-orbital

Zn forms Zn²⁺, and has a full d-orbital

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4
Q

what are the 3 characteristic properties of transition elements?

A
  • form compounds in which the transition element has different oxidation states
  • form coloured ions
  • the elements and their compounds can act as catalysts
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5
Q

ligand

A

molecule or ion that donates a pair of electrons to a central metal ion to form a coordinate bond

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6
Q

example of complex ion with six-fold coordination with an octahedral shape

A

[Cu(H₂O)₆]²⁺

[Fe(H₂O)₆]³⁺

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7
Q

example of complex ion with four-fold coordination with a tetrahedral shape

A

[CuCl₄]²⁻

[CoCl₄]²⁻

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8
Q

example of complex ion with four-fold coordination with a planar shape

A

[Pt(NH₃)₂Cl₂]

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9
Q

coordination number

A

no. coordinate bonds attached to the central metal ion

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10
Q

what is a monodentate ligand?

A

a ligand that is able to donate one pair of electrons to a central metal ion
eg. H₂O, NH₃, Cl⁻

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11
Q

what is a bidentate ligand?

A

a ligand that is able to donate two pairs of electrons to a central metal ion
eg. NH₂CH₂CH₂NH₂, ⁻OOCCOO⁻

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12
Q

what’s the bond angle for an octahedral complex ion with 6 coordinate bonds?

A

90°

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13
Q

what’s the bond angle for an tetrahedral complex ion with 4 coordinate bonds?

A

109.5°

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14
Q

what’s the bond angle for an square planar complex ion with 4 coordinate bonds?

A

90°

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15
Q

what are the two types of stereoisomerism that complex ions display?

A
  • cis-trans

- optical

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16
Q

what type of complex ions does cis-trans isomerism occur in?

A

square planar eg. [Pt(NH₃)₂Cl₂]

octahedral eg. [Co(NH₃)₄Cl₂]⁺

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17
Q

what type of complex ions does optical isomerism occur in?

A

octahedral complexes containing two or more bidentate ligands eg. [Ni(NH₂CH₂CH₂NH₂)₃]²⁺

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18
Q

what is cis-platin and what are its uses?

A

[Pt(NH₃)₂Cl₂] (square planar)
anti-cancer drug as it attacks tumours
forms a platinum complex inside a cell that binds to DNA and prevents cell division. Causes apoptosis.

19
Q

ligand substitution reaction of [Cu(H₂O)₆]²⁺ with excess ammonia and colour change

A

[Cu(H₂O)₆]²⁺ + 4NH₃ → [Cu(NH₃)₄(H₂O)₂]²⁺ + 4H₂O

pale blue solution → dark blue solution

20
Q

ligand substitution reaction of [Cu(H₂O)₆]²⁺ with excess concentrated HCl and colour change

A

[Cu(H₂O)₆]²⁺ + 4Cl⁻ ⇌ [CuCl₄]²⁻ + 6H₂O
pale blue solution → yellow solution
octahedral changes to tetrahedral (coordination no. changes as Cl⁻ are larger than H₂O ligands and fewer can fit around the Cu²⁺ ion

21
Q

what is formed if [Cu(H₂O)₆]²⁺ reacts with a small amount of ammonia?

A

Cu(OH)₂
blue precipitate
this dissolves in excess ammonia to form a dark blue solution of [Cu(NH₃)₄(H₂O)₂]²⁺

22
Q

ligand substitution reaction of [Cr(H₂O)₆]³⁺ with excess ammonia and colour change

A

[Cr(H₂O)₆]³⁺ + 6NH₃ → [Cr(NH₃)₆]³⁺ + 6H₂O

violet solution → purple solution

23
Q

what is formed if [Cr(H₂O)₆]³⁺ reacts with a small amount of ammonia?

A

Cr(OH)₃
grey-green precipitate
this dissolves in excess ammonia to form a purple solution of [Cr(NH₃)₆]³⁺

24
Q

what’s the biochemical importance of Fe²⁺ in Hb?

A

Fe²⁺ binds to O₂, forming oxyhaemoglobin and enabling oxygen to be transported in blood

25
Q

what happens when you breath in CO?

A

ligand substitution reaction happens where O₂ is replaced by CO in the coordinate bond, forming carboxyhaemoglobin. This is irreversible as CO binds more strongly than O₂

26
Q

Cu²⁺ with NaOH(aq) observations and ionic eq.

A

pale blue solution → blue precipitate of Cu(OH)₂
Cu²⁺(aq) + 2OH⁻(aq) → Cu(OH)₂(s)

precip is insoluble in excess NaOH

27
Q

Fe²⁺ with NaOH(aq) observations and ionic eq.

A

pale green solution → green precipitate of Fe(OH)₂
Fe²⁺(aq) + 2OH⁻(aq) → Fe(OH)₂(s)

precip is insoluble in excess NaOH
precip is oxidised in air to Fe(OH)₃ (orange-brown precip)

28
Q

Fe³⁺ with NaOH and NH₃(aq) observations and ionic eq.

A

pale yellow solution → orange-brown precipitate of Fe(OH)₃
Fe³⁺(aq) + 3OH⁻(aq) → Fe(OH)₃(s)

precip is insoluble in excess NaOH & and NH₃

29
Q

Mn²⁺ with NaOH and NH₃(aq) observations and ionic eq.

A

pale pink solution → light brown precipitate of Mn(OH)₂
Mn²⁺(aq) + 2OH⁻(aq) → Mn(OH)₂(s)

precip is insoluble in excess NaOH & and NH₃
precip darkens in air

30
Q

Cr³⁺ with NaOH and NH₃(aq) observations and ionic eq.

A

violet solution → grey-green precipitate of Cr(OH)₃
Cr³⁺(aq) + 3OH⁻(aq) → Cr(OH)₃(s)

precip is soluble in excess NaOH, forming dark green solution of [Cr(OH)₆]³⁻
Cr(OH)₃(s) + 3OH⁻(aq) → [Cr(OH)₆]³⁻(aq)

precip is soluble in excess NH₃, forming [Cr(NH₃)₆]³⁺ which is purple

31
Q

colour of [Cu(H₂O)₆]²⁺

A

pale blue solution

32
Q

colour of [Cu(NH₃)₄(H₂O)₂]²⁺

A

dark blue solution

33
Q

colour of Cu(OH)₂

A

blue precipitate

34
Q

colour of [CuCl₄]²⁻

A

yellow solution

35
Q

colour of [Cr(H₂O)₆]³⁺

A

violet solution

36
Q

colour of [Cr(NH₃)₆]³⁺

A

purple solution

37
Q

colour of Cr(OH)₃

A

grey-green precipitate

38
Q

colour of Fe(OH)₂

A

green precipitate

39
Q

colour of [Fe(H₂O)₆]²⁺

A

pale green solution

40
Q

colour of [Fe(H₂O)₆]³⁺

A

pale yellow solution

41
Q

colour of Fe(OH)₃

A

orange-brown precipitate

42
Q

colour of [Mn(H₂O)₆]²⁺

A

pale pink solution

43
Q

colour of Mn(OH)₂

A

light brown precipitate