unit 1a: transition metals Flashcards

1
Q

transition metals

A

metals with an incomplete d-subshell in at least one of their ions

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2
Q

variable valency

A

transition metals can form ions with different charges by losing different numbers of electrons

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3
Q

scandium and zinc

A

these are not transition metals as there is not an incomplete d-subshell in the ions they form

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4
Q

properties

A

form coloured ions, form complexes, variable oxidation states, show catalytic activity

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5
Q

oxidation state

A

an element is said to be in a particular oxidation state when it has a specific oxidation number, related to the number of electrons the species has lost or gained

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6
Q

oxidation number in a free element

A

0 e.g. Mg=0 and Cl2=0

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7
Q

for monatomic ions, the oxidation number is

A

equal to the charge, e.g. Cl^-1=-1 and Al^3+=+3

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8
Q

oxidation number for oxygen

A

-2

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9
Q

oxidation number for hydrogen

A

+1

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10
Q

group 1 metals and group 2 metals

A

+1 and +2

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11
Q

oxidation number in compounds

A

fluorine, the CN^-1 ion, and all of group 7 is always equal to -1

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12
Q

in molecule the sum of all oxidation numbers is

A

equal to 0, e.g. H20=0

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13
Q

in a polyatomic ion, the sum of the oxidation numbers is

A

equal to the charge of the ion, e.g. SO4^2-=-2

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14
Q

oxidation involves

A

increase in oxidation number

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15
Q

reduction involves

A

decrease in oxidation number

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16
Q

metals high in oxidation states tend to be good

A

oxidising agents

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17
Q

what two elements in the box are not transition metals

A

scandium and zinc

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18
Q

redox acronym

A

OILRIG

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19
Q

ligand definition

A

electron donors, may be negative ions or molecules with non-bonding pairs of electrons

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20
Q

a complex consists of

A

a central metal ion surrounded by ligands

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21
Q

dative bond

A

when both electrons of the shared pair come from the same atom

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22
Q

ligands have at least

A

one lone pair of electrons

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23
Q

monodentate

A

when a ligand uses just one atom to bind to the central metal

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24
Q

bidentate

A

when a ligand uses two atoms to bind to the central metal

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25
Q

example of a hexadentate ligand

A

ethylenediaminetetraacetate- EDTA

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26
Q

monodentate ligands- negative ions

A

fluoride F- , chloride Cl- , cyanide CN-

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27
Q

monodentate ligands- neutral molecules

A

water H2O , ammonia NH3

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28
Q

bidentate ligand- negative ion

A

oxalate C2O4^2-

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29
Q

coordination number

A

the total number of bonds from the ligands to the central transition metal atom/ion

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30
Q

if the complex ion is negative the transition metal name will end in

A

-ate

31
Q

if the ligand is a negative ion the name in complex will

A

replace the “e” ending with “o” e.g. bromine —> bromido

32
Q

CO name in complex ion

A

carbonyl

33
Q

H2O name in complex ion

A

aqua

34
Q

NH3 name in complex ion

A

ammine

35
Q

Fe name in complex ion

A

ferrate

36
Q

Cu name in complex ion

A

cuprate

37
Q

coordination compound

A

when a complex ion combines with oppositely charged ions

38
Q

if the complex is a positive ion it will appear

A

first in the formula and the name

39
Q

if the complex is a negative ion

A

it will appear last in the formula and the name

40
Q

three primary colours of visible light

A

red , green , and blue

41
Q

complementary colour

A

transmitted light from certain chemicals(when white light shines on certain chemicals they may absorb some of the. visible light, the colour we see is the white light minus absorbed light)

42
Q

when red light is absorbed

A

blue and green are transmitted and cyan is observed

43
Q

when blue light is absorbed

A

red and green are transmitted and yellow is observed

44
Q

when green light is absorbed

A

red and blue are transmitted and magenta is observed

45
Q

a more concentrated soloution will absorb more

A

light than a dilute solution and be darker in colour

46
Q

extent of d orbital splitting factors

A

the metal involved , the oxidation state of the metal , the nature of the ligand

47
Q

spectra chemical series

A

CN-, NH3, H2O, OH-, F-, Cl-, Br-, I-

48
Q

start of the spectrochemical series

A

weaker field , smaller delta , longer wavelength

49
Q

end of the spectrochemical series

A

stronger field , larger delta , shorter wavelength

50
Q

weakest at splitting d orbitals

A

I-

51
Q

strongest at splitting d orbitals

A

CO

52
Q

crystal field theory

A

explains how transition metals (with an incomplete 3d subshell) are coloured, only applies to octahedral complexes

53
Q

splitting

A

as a result of ligands approaching and bonding to the metal, the five 3d orbitals are no longer degenerate

54
Q

delta

A

the splitting energy

55
Q

d to d transition

A

when any of the three lower d orbitals absorb energy and are promoted to one of the two higher energy d orbitals

56
Q

how the metals transmit the colours

A

if the energy absorbed is equal to a wavelength of light in the visible spectrum, the compound will transmit its complementary colour

57
Q

catalyst of the haber process

A

iron

58
Q

catalyst of the contact process

A

vanadium (V) oxide

59
Q

catalyst of the ostwald process

A

platinum

60
Q

catalyst for catalytic converters in cars

A

platinum , palladium , rhodoum

61
Q

catalyst for the production of methanol

A

copper

62
Q

catalyst for the hardening of oils to fats

A

nickel

63
Q

catalyst for the polymerisation of alkenes

A

titanium compounds

64
Q

how catalysts speed up chemical reactions

A

by providing an alternative reaction pathway of lower activation energy

65
Q

why do many transition metals act as catalysts

A

due to their ability to exist in a variety of different oxidation states

66
Q

how do ligands form complexes with metal atoms

A

donate pairs of electrons

67
Q

homogeneous

A

same state as reactants, change their oxidation allowing formation of intermediate complexes, then reverts back to its original state

68
Q

heterogeneous

A

different state as reactants, work by absorption of the reactant molecules to their active sites, presence of unpaired d-electron allow activated complex to form providing an alternative pathway and activation energy

69
Q

how do transition metals act as catalysts

A

unpaired d electrons (donating and accepting electrons)

70
Q

how do unpaired electrons arise in H20 easier than in CN-

A

H2O has a smaller splitting energy so it is easier for electrons to jump up to the higher energy d orbitals

71
Q

why are transition metals coloured

A

light is absorbed when electrons in lower energy d orbitals are promoted in a d-d transition, if the energy absorbed is visible light then it will be coloured

72
Q

changing the ligand in a complex can

A

change the colour

73
Q

a complex may be colourless because

A

it was in the UV spectrum, it has a full d subshell

74
Q

what causes d orbital splitting

A

lone pairs of electrons in the ligand