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A-level Chem > Transition metals > Flashcards

Transition metals Flashcards

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1
Q

Transition metal row and how the characteristics arise

A

Sc->Cu

arise from an incomplete d sublevel in atoms or ions

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2
Q

4 transition metal characteristics

A

complex formation
formation of coloured ions
variable oxidation states
catalytic activity

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3
Q

Why is zinc not a transition metal

A

only forms 2+ ions
has a complete d orbital as a 2+ ion
does not meet “incomplete d orbital in a compound” criteria

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4
Q

complex definition

A

central metal ion surrounded by ligands

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5
Q

ligand definition

A

atom/ion/molecule that can donate a lone electron pair

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6
Q

coordinate bond definition

A

shared pair of electrons in the covalent bond come from one of the bonding atoms

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7
Q

3 monodentate ligands

A

H2O
NH3
Cl-

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8
Q

2 bidentate ligands

A

1,2-diaminoethane
ethanedioate ion (C2O42-)

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9
Q

multidentate ligand

A

EDTA4-

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10
Q

which monodentate ligand can displace the other 2?

A

Cl- as it is larger

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11
Q

chelate effect

A

monodentate ligand substituted by a bidentate/multidentate ligand for a more stable complex
due to positive entropy change as theres more moles of products than reactants

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12
Q

Why is it useful that EDTA is stable?

A

add to rivers to remove heavy metal ions as EDTA complexes aren’t toxic

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13
Q

What does a transition metal’s complex colour depend on?

A

coordination number of the complex
type of ligand bonded to the ion
oxidation state

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14
Q

how is colour observed

A

the transition metal complex absorbs certain wavelengths, exciting electrons into a higher energy level and the remaining wavelengths are reflected and transmitted to the eye

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15
Q

change in energy (plancks constant eqn) and what the letters mean + units

A

ΔE= hc/λ = hυ

h plancks constant 6.63x10-34
λ wavelength in m
υ frequency in Hz

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16
Q

describe colorimetry

A

analytical technique
uses absorption of visible light
to determine conc of coloured ions
by measuring absorbance

17
Q

calibration graph axes

A

x = concentration
y = absorbance

18
Q

Oxidation states of vanadium, ion formulae of each and ion colours

A

5 VO2+ yellow
4 VO^2+ blue
3 V3+ green
2 V2+ violet

You Better Get Vanadium

19
Q

Reduction reaction of vanadium with zinc, requiring acidic conditions?

A

standard balanced acidic condition redox reaction with bigger oxidation number on left

20
Q

Tollens reagent test for aldehydes equation

A

RCHO + 2[Ag(NO3)2]+ + 2OH- ->
RCOO- + 2Ag + 4NH3 + 2H2O

21
Q

C2O4 2- redox titration products

A

2CO2 + 2e-

22
Q

heterogenous catalyst example

A

haber process solid iron catalyst for hydrogen and nitrogen gas reaction

23
Q

why do transition metals make good catalysts

A

variable oxidation states
electrons are transferred to produce a reactive intermediate
this speeds up reaction rate

24
Q

Heterogenous reaction overall equation and intermediate reactions

A

2SO2 + O2 -V2O5> 2SO3

2V2O5 + 2SO2 -> 2V2O4 + 2SO3
2V2O4 + O2 -> 2V2O5

25
Q

Catalyst adsorption

A

solid catalysts adsorb molecules onto an active site on the surface of the catalyst

these active sites increase proximity of molecules + weaken covalent bonds + increasing rate of reaction

26
Q

what is catalyst poisoning?

A

impurities block active sites of heterogenous catalysts
molecule’s covalent bonds stay intact
catalyst has no effect on ROR

27
Q

the problem with catalyst poisoning + an example of it

A

increased chemical production costs
catalyst must be replaced/cleaned regularly
sulfur impurities poison the solid iron catalyst in the Haber process

28
Q

Homogenous catalyst overall equation and intermediate reactions

A

S2O8 2- + 2I- -Fe2+> I2 + 2SO4 2-

S2O8 2- + 2Fe2+ -> 2Fe3+ + 2SO4 2-
2Fe3+ + 2I- -> 2Fe2+ + I2

29
Q

Why is a Fe2+ catalyst needed for S2O82- and 2I- to react?

A

energy needed to overcome repulsive forces as they’re both negatively charged

30
Q

autocatalysis reaction is

A

a redox reaction between MnO4- ions and C2O42-

31
Q

during colorimetry, what must be done before taking absorbance

A

add an appropriate ligand to intensify the colour

A-level Chem (35 decks)

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