23 transition metals

Question 1

how do you define a transition element?

Answer 1

an element that forms at least one stable ion with a partially filled d sub shell

Question 2

why is scandium not a transition element?

Answer 2

only forms Sc3+ which makes a non-partially filled d sub shell (3d0)

Question 3

give 4 features of a transition element

Answer 3

1. forms complex ions
2. coloured ions
3. catalytic properties
4. variable oxidative states

Question 4

define a co-ordinate bond

Answer 4

a shared pair of electrons where both electrons come from the same atom

Question 5

define a ligand

Answer 5

a lone pair of electrons which can form a co-ordinate bond with a transition metal ion

Question 6

define coordination number

Answer 6

number of coordinate bonds formed

Question 7

define complex ion

Answer 7

central atom/ion surrounded by ligand

Question 8

what is a:
monodentate ligand?
bidentate ligand?
multidentate ligand?

Answer 8

monodentate- each ligand forms 1 coordinate bond
bidentate- each ligand forms 2 coordinate bonds
multidentate ligand- each ligand forms 2 or more coordinate bonds

Question 9

what are 5 monodentate ligands?

Answer 9

:H2O
:NH3
:Cl
:OH-
:CN

Question 10

what are 2 bidentate ligands?

Answer 10

1,2-diaminoethane
ethanedioate ion

Question 11

what is the structural formula for 1,2-diaminoethane?

Answer 11

NH2CH2CH2NH2

Question 12

what does an ethanedioate ion look like?

Answer 12

2 carbons
double bond O attached to each
single bond :O- attached to each

Question 13

what are 4 common shapes transition metal complexes can form?

Answer 13

octahedral
linear
square planar
tetrahedral

Question 14

how many bonds does each shape transition metal complexes can form have?

Answer 14

octahedral- 6
linear- 2
tetrahedral- 4
square planar- 4

Question 15

give 2 examples of complexes that form octahedral shapes

Answer 15

[Cu(H2O)]2+
[Co(NH3)6]2+

Question 16

give an example of a complex with a tetrahedral shape

Answer 16

[CoCl4]2-

Question 17

why can’t transition metals with Cl ligand be octahedral?

Answer 17

because Cl ions are large and only 4 can fit around the transition metal

Question 18

give an example of a complex with a square planar shape

Answer 18

[Ni(CN)4]2-

Question 19

give the structural formula of the complex that forms an octahedral shape with multidentate ligands

Answer 19

[Ni(NH2CH2CH2NH2)3]2+

Question 20

name a hexadentate ligand

Answer 20

EDTA4-

Question 21

what shape does EDTA4- form in a complex?

Answer 21

octahedral

Question 22

what is a ligand substitution reaction?

Answer 22

when a ligand attached to the transition metal ion is replaced by a different ligand

Question 23

give the equation to show how the complex [CU(H2O)6]2+ can be turned into [CU(H2O)3(NH3)3]2+

Answer 23

[Cu(H2O)6]2+ + 3NH3 –> [Cu(H2O)3(NH3)3]2+ + 3H2O

Question 24

give the equation to show how [Cu(H2O)6]2+ can be turned into [CuCl4]2-

Answer 24

[Cu(H2O)6]2+ + 4Cl- –> [CuCl4]2- + 6H2O

Question 25

what is the chelate effect?

Answer 25

when a monodentate ligand is substituted by a bidentate ot multidentate ligand and a large increase of entropy occurs

Question 26

why does a large increase of entropy occur when a monodentate ligand gets replaced by a bidentate or a multidentate ligand?

Answer 26

because there is an increase in molecules on the right hand side of the equation

Question 27

define stereoisomer

Answer 27

same structural formula but different arrangement of atoms in space

Question 28

what are the two types of stereoisomerism transition metals can display?

Answer 28

geometrical and optical

Question 29

what is a cis isomer in an octahedral complex?

Answer 29

where alike ligands are arranged next to each other at a 90° angle

Question 30

what is a trans isomer in an octahedral complex?

Answer 30

where alike ligands are arranged opposite from each other at a 180° angle

Question 31

what is a cis isomer in a square planar complex?

Answer 31

if alike ligands are next to each other

Question 32

what is a trans isomer in a square planar complex?

Answer 32

if alike ligands are apposite to one another

Question 33

what is the structural formula for cisplatin?

Answer 33

[PtCl2(NH3)2]

Question 34

what is cisplatin?

Answer 34

a very effective anti-caner drug when it is a cis isomer

Question 35

how does cisplatin work?

Answer 35

binds to cancerous cells to stop cell replication (Cl- on cisplatin are substituted for N on guanine)

Question 36

what are the colours that make up white light?

Answer 36

red orange yellow green blue indigo violet

Question 37

which colours in white light have lower energy?

Answer 37

red orange yellow

Question 38

which colours in white light have higher energy?

Answer 38

blue indigo violet

Question 39

why are most transition metal compounds coloured?

Answer 39

partially filled d sub shell absorbs some of the colours from white light and transmits other colours

Question 40

what do the electrons in the d orbital need to be excited?

Answer 40

energy from white light

Question 41

where are the d orbital electrons excited to and from?

Answer 41

ground state to excited state

Question 42

how do you calculate the change in energy absorbed by electrons?

Answer 42

ΔE = hv or ΔE = h c/λ

Question 43

what do the letters in ΔE = hv stand for?

Answer 43

ΔE - change in energy h - Planck's constant (J s) v- frequency of light ( s-1)

Question 44

what do the letters in ΔE = h c/λ stand for?

Answer 44

ΔE - change in energy h - Planck's constant (J s) c - speed of light λ - wavelength of light (m)

Question 45

how many m is 1nm

Answer 45

1x10^-9

Question 46

what does big e BIV abs mean?

Answer 46

1. transition metal has large ΔE between d sub shells 2. high energy light 3. will be absorbed to excite electrons 4. ROY will be transmitted to make compound look red

Question 47

what does small e ROY abs mean?

Answer 47

1. transition metal has a small ΔE between d sub shells 2. low energy light 3. will be absorbed to excite electrons 4. BIV will be transmitted to make compound look blue

Question 48

what changes could alter the colour of a compound?

Answer 48

1. change in Ligands 2. change in Oxidation states 3. change in Coordination number 4. change in Shape of complex

Question 49

what apparatus can you use to measure the amount of light absorbed?

Answer 49

colorimeter

Question 50

how does a colorimeter work?

Answer 50

1. light source shines a light of specific frequency through solution 2. some light absorbed some light transmitted 3. transmitted light hits the detector 4. detector gives reading for the amount of light which passed through

Question 51

what does a 1.0 transmittance reading mean in colorimetry?

Answer 51

that all the light passed through the sample and none was absorbed

Question 52

what can colorimetry also be used to determine?

Answer 52

an unknown concentration of a transition metal ion

Question 53

how can colorimetry determine an unknown concentration of a transition metal ion?

Answer 53

1. measure absorbance of known concentrations 2. plot graph: absorbance against concentration 3. read value of conc for measured absorbance from graph

Question 54

what physical factor when doing a colorimetry test affects the amount of absorption?

Answer 54

length of container affects distance light has to travel

Question 55

what does a filter do in colorimetry?

Answer 55

only lets one colour of light through sample

Question 56

what does placing a cuvette filled with water into colorimeter and setting to zero do?

Answer 56

ensures accuracy and negates absorbance due to solvent

Question 57

what is a catalyst?

Answer 57

a substance that increases the rate of reaction without being used up

Question 58

how does a catalyst work?

Answer 58

by providing an alternative pathway with a lower activation energy

Question 59

when a catalyst is added, which way does Ea move on a maxwell boltzmann distributon?

Answer 59

to the left

Question 60

what is a heterogeneous and a homogeneous catalyst?

Answer 60

heterozygous- where the catalyst is in a different phase to the reactants homozygous- where the catalyst is in the same phase as the reactants

Question 61

what state is a heterogeneous catalyst usually in?

Answer 61

solid

Question 62

list the steps of a heterogeneous catalyst

Answer 62

1. reactants adsorb onto surface of catalyst on active site 2. reaction occurs on surface of catalyst (bonds weaken) 3. products desorb from the surface of catalyst

Question 63

what does adsorb mean?

Answer 63

stick

Question 64

what ate 3 heterogeneous catalyst examples?

Answer 64

1. solid iron making ammonia in the haber process 2. solid V2O5 making sulfuric acid 3. solid chromium (III) manufacture of methanol

Question 65

what is the equation that solid iron catalyses?

Answer 65

making ammonia in the haber process: N2(g) + 3H2(g) ⇌ 2NH3(g)

Question 66

what is the equation that solid V2O5 catalyses?

Answer 66

making sulfuric acid in the contact process SO2(g) + V2O5(s) ⇌ SO3(g) + VsO4(s) 2V2O4(s) + O2(g) ⇌ 2V2O5 2SO2(g) + O2(g) -> 2SO3 sulfuric acid formed by reacting with water

Question 67

what is the equation that solid chromium(III) catalyses?

Answer 67

manufacture of methanol CO(g) + 2H2(g) -> CH3OH(g)

Question 68

what state are the majority of homogeneous catalysts and reactants in?

Answer 68

aqueous

Question 69

why can transition metals act as catalysts?

Answer 69

they have variable oxidation states

Question 70

why can't group 1 metals be catalysts?

Answer 70

they only exist in one oxidation state

Question 71

give an example of a homogeneous catalyst

Answer 71

Fe2+

Question 72

what is the equation that Fe2+ catalyses?

Answer 72

S2O8^2- + 2I- -> 2SO4^2- +2Fe3+ 2I- + 2Fe3+ -> I2 +2Fe2+ (all states aqueous)