Transition Metals

Question 1

what is a transition metal?

Answer 1

metals that can form one or more stable ions w a partially filled d sub-shell

Question 2

where are transition metals found in periodic table?

Answer 2

d-block

Question 3

which orbital fills first 3d or 4s? And what is the exception in two transition metals?

Answer 3

4s fills first
Cr and Cu are exceptions
- Cr prefers to have 1 electron in each orbital of 3d sub-shell & just 1 in 4s sub-level, gives it more stability
- Cu prefers to have full 3d sub-level and just 1 electron in 4s sub-level, more stable

Question 4

which orbital are electrons lost first from, 3d or 4s?

Answer 4

4s

Question 5

why aren’t Sc and Zn transition elements?

Answer 5

Sc forms one ion Sc^3+ which has an empty 3d sub-level
Zn forms one ion Zn^2+ which has a full 3d sub-level
(transition metals form stable ions with PARTIALLY filled d sub-levels)

Question 6

physical properties of transition metals

Answer 6

high density
high MP and BP
‘same’ ionic radii (more or less)

Question 7

chemical properties of transition metals

Answer 7

they act as good catalysts
they exist in variable oxidation states
they can form complex ions
they can form coloured ions in solution

Question 8

why do transition metals have variable oxidation states?

Answer 8

• the electrons sit in 4s and 3d energy levels which are very close
• so electrons are gained and lost using similar amount of energy when they form their ions

Question 9

what ions do Scandium form and state oxidation states?

Answer 9

Sc^3+ (Oxidation state: +3)

Question 10

what ions do Vanadium form and state oxidation states?

Answer 10

V2+ (+2), V^3+ (+3), VO^2+ (+4), VO2+ (+5)

Question 11

what ions do Chromium form and state oxidation states?

Answer 11

Cr^3+ (+3) and Cr2O7^2- (+6)

Question 12

what ions do Manganese form and state oxidation states?

Answer 12

Mn^2+ (+2) and MnO4- (+7)

Question 13

what ions do Iron form and state oxidation states?

Answer 13

Fe^2+ (+2) and Fe^3+ (+3)

Question 14

what ions do Cobalt form and state oxidation states?

Answer 14

Co^2+ (+2)

Question 15

what ions do Nickel form and state oxidation states?

Answer 15

Ni^2+ (+2)

Question 16

what ions doCopper form and state oxidation states?

Answer 16

Cu^2+ (+2)

Question 17

what ions do Zinc form and state oxidation states?

Answer 17

Zn^2+ (+2)

Question 18

state colours of vanadium ions formed

Answer 18

V2+ violet when surrounded by 6H2O, they’re normally substituted so usually look green
V^3+ green
VO^2+ blue
VO2+ yellow

Question 19

state colours of chromate and dichromate ions formed

Answer 19

Cr2O7^2- orange

Cr^3+ violet, 6H20 usually substituted so appears green sometimes

Question 20

state colours of Manganate ions formed

Answer 20

MnO4^- purple

Mn^2+ pale pink

Question 21

state colours of Iron ions formed

Answer 21

Fe^2+ pale green

Fe^3+ orange/yellow

Question 22

state colours of Cobalt ion formed

Answer 22

Co^2+ pink

Question 23

state colours of Nickel ion formed

Answer 23

Ni^2+ green

Question 24

state colours of Copper ion formed

Answer 24

Cu^2+ blue

Question 25

what is a complex?

Answer 25

central atom or ion surrounded by co-ordinatedly bonded ligands

Question 26

what is a co-ordinate bond?

Answer 26

(or dative covalent bond) covalent bond where both electrons are in shared pair come from SAME atom - in a complex they come from the ligands

Question 27

what is a ligand?

Answer 27

- atom/ion/molecule that donates a pair of electrons to central transition metal ion to form a co-ordinate bond (they must have at least 1 pair of lone electrons) - can be monodentate, bidentate or polydentate

Question 28

what is the co-ordinate number?

Answer 28

the number of co-ordinate bonds that are formed with the central metal ion (not the number of ligands)

Question 29

monodentate ligands

Answer 29

``` ligands which have one lone pair of electrons examples: H2O: :NH3 :Cl- ```

Question 30

bidentate ligands

Answer 30

ligands which have two lone pairs of electrons examples: ethanedioate C ₂O²⁻ ₄ ethane-1,2-diamine C₂H₄(NH₂)

Question 31

multidentate ligands

Answer 31

ligand capable of donating two or more pairs of electrons (to from co-ordinate bonds) examples: Haem EDTA^4- (forms 6 co-ordinate bonds w central metal ion)

Question 32

which are small ligands and what does this mean for complex shapes?

Answer 32

H2O: :NH3 - means 6 can fit around central metal ion forming octahedral shape (bond angles 90 degrees)

Question 33

which are bigger ligands and what does this mean for complex shapes?

Answer 33

:Cl- - can only fit 4 ligands around central metal ion (usually forming tetrahedral shape, bond angle is 109.5 degrees, BUT can also form square planar e.g. cisplatin bond angles 90 degrees)

Question 34

what kind of size are these ligands: ethanedioate and ethane-1,2-diamine? and how many can fit around a central ion?

Answer 34

- they are 'larger' (than the other ones e.g. :Cl-) | - three

Question 35

complexes with co-ordinate number two form what coplex shapes? Give an example

Answer 35

- form linear shapes (bond angle is 180 degrees) | - some silver complexes e.g. [Ag(NH3)2}+ (this is tollens reagent/silver mirror)

Question 36

How do you work out oxidation state of metal ion?

Answer 36

total oxidation state - total oxidation state of ligands

Question 37

a complex's overall charge is the same as its what?

Answer 37

its total oxidation state (number and charge outside square bracket)

Question 38

what is haem?

Answer 38

a multidentate ligand that is found in molecule haemoglobin

Question 39

what is haemoglobin?

Answer 39

quarternary protein used to transport oxygen around body in blood

Question 40

what do the ligands NH3 and H2O have in common?

Answer 40

similar in size and are uncharged

Question 41

exchnage of ligands NH3 and H2O occurs without what?

Answer 41

without change of co-ordination number (eg Co2+ and Cu2+)

Question 42

what occurs when you dissolve the salt of a transition metal in water?

Answer 42

- becomes surrounded by water molceules acting as ligands | called aqua ions

Question 43

what kind of isomers can transition metals form?

Answer 43

optical isomers and geometric (E-Z) isomers

Question 44

what kind of complexes does geometric isomerism occur in?

Answer 44

octahedral and square planar

Question 45

in what complexes does optical isomerism occur?

Answer 45

- this occurs when there are two or more bidentate ligands in a complex