Unit 2: Section 4 - Transition Metals

Question 1

Definition : transitional metal

Answer 1

A metal that can form one or more stable ions with a partially filled d sub-level.

Question 2

Which metals in the d-block are not transition metals?

Answer 2

scandium only forms one ion Sc ^3+ with an empty d sub-level.
zinc only forms one ion Zn^2+ with a full d sub-level

Question 3

Transitional metals: physical properties (3)

Answer 3

1) high density
2) high melting point and high boiling point
3) ionic radii are more or less the same

Question 4

transitional metals: chemical properties (4)

Answer 4

1) form complex ions
2) form colored ions
3) good catalysts
4) exist in variable oxidation states

Question 5

Color: MnO4 -

Answer 5

purple

Question 6

Color: Cr2O7 2-

Answer 6

orange

Question 7

Color: VO2 +

Answer 7

yellow

Question 8

Color: VO 2+

Answer 8

blue

Question 9

Color: V 3+

Answer 9

green

Question 10

Color: Cr 3+

Answer 10

violet / green

Question 11

Color: Fe 3+

Answer 11

purple / yellow

Question 12

Color: V 2+

Answer 12

violet

Question 13

Color: Mn 2+

Answer 13

pale pink

Question 14

Color: Fe 2+

Answer 14

pale green

Question 15

Color: Co 2+

Answer 15

pink

Question 16

Color: Ni 2+

Answer 16

green

Question 17

Color: Cu 2+

Answer 17

blue

Question 18

Definition: a complex

Answer 18

A central metal atom or ion surrounded by coordinately bonded ligands.

Question 19

Definition: a co-ordinate bond

Answer 19

a covalent bond in which both electrons in the shared pair come from the same atom.

Question 20

Definition: ligand

Answer 20

an atom, ion or molecule that donates a pair of electrons to a central transitional metal ion to form a co-ordinate bond.

Question 21

Definition: co-ordination number

Answer 21

the number of co-ordinate bonds that are formed with the central metal ion.

Question 22

What shape will a complex be with six co-ordinate bonds?

Answer 22

An octahedral shape with 90 degree angles.

Question 23

What shape will a complex be with 4 co-ordinate bonds?

Answer 23

A tetrahedral shape with 109.5 degree angles or a square planar shape with 90 degree angles.

Question 24

What shape will a complex be with 2 co-ordinate bonds?

Answer 24

A linear shape with 180 degree bond angle.

Question 25

Formula for the oxidation state of the metal ion

Answer 25

total oxidation state - the sum of the oxidation states of the ligands

Question 26

Definition: multidentate

Answer 26

ligands that can form more than one co-ordinate bond

Question 27

Definition: monodentate

Answer 27

ligands can only form one co-ordinate bond

Question 28

What happens to haemoglobin in the lungs?

Answer 28

The oxygen concentration is high, an oxygen molecule substitutes the water ligand and bonds coordinately to the Fe (II) ion to form oxyhaemoglobin, which is carried around the body in the blood,

Question 29

What happens to haemoglobin in muscle tissue?

Answer 29

The oxygen molecule is exchanged for a water molecule and the heamoglobin returns to the lungs again.

Question 30

Components of haemoglobin

Answer 30

Fe 2+, H2O , four N , globin protein (another N)

Question 31

Definition: optical isomerism

Answer 31

where an ion can exist in two forms that are non-superimposable mirror images.

Question 32

cis- isomerism

Answer 32

If two odd ligands are next to each other

Question 33

trans- isomerism

Answer 33

if the two odd ligands are opposite each other

Question 34

How do ligands split the 3d Sub-level into two energy levels?

Answer 34

3d orbitals of transition element ions all have the same energy. When ligands bond to the ions some of the orbitals gain energy which splits the 3d orbitals to two different energy levels.

Question 35

How do electrons jump to higher orbitals?

Answer 35

Electrons tend to occupy lower orbitals and to jump up to the higher orbitals they need energy equal to the energy gap. They get this from visible light.

Question 36

How is energy absorbed (AE), Planck's constant (h), frequency of light absorbed (v)

Answer 36

AE = hv

Question 37

How are the colors of compounds formed?

Answer 37

When visible light hits a transition metal ion, some frequencies are absorbed when electrons jump up to the higher orbitals. The frequencies absorbed depend on the size of the energy gap. The rest of the frequencies are transmitted or reflected. These transmitted or reflected frequencies combine to make the complement of the color of the absorbed frequencies.

Question 38

Factors which can affect the size of the energy gap (3)

Answer 38

1) changes in oxidation 2) changes in co-ordination number 3) changes in ligand

Question 39

How can spectroscopy be used to find concentrations of transition metal ions?

Answer 39

White light is shone through a filter which is chosen to only let through the color of light that is absorbed by the sample. The light passes through the sample to a colorimeter, which calculates how much light was absorbed by the sample. The more concentrated a colored solution is, the more light it will absorb.

Question 40

Aluminum hydroxide precipitate + sodium hydroxide excess

Answer 40

will dissolve because it's amphoteric

Question 41

copper hydroxide precipitate + ammonia excess

Answer 41

dissolves because it undergoes a ligand exchange reaction with excess ammonia

Question 42

sodium carbonate + Fe 3+/ Fe 2+

Answer 42

Fe 3+ will give off a gas whilst Fe 2+ will not