15.1

Question 1

define transition metal

Answer 1

an element that forms one or more stable ions with an incompletely filled d-orbitals

Question 2

what are the characteristics of transition metals

Answer 2

are hard solids
high mp & bp
can act as a catalyst
form coloured ions & compounds
form ions with different oxidation states
form ions with incompletely filled d-orbitals

Question 3

which 2 out of 10 elements in the d-block elements of period 4 are not transition metals and why

Answer 3

scandium & zinc
because they only form one ion and their compounds are not coloured

Question 4

what is the electronic configuration of chromium

Answer 4

[Ar] 4s1 3d5

Question 5

what is the electronic configuration of copper

Answer 5

[Ar] 4s1 3d10

Question 6

how do transition metals lose electrons when they form ions

Answer 6

they lose electrons from their 4s subshell first then 3d

Question 7

why are ions with high oxidation numbers less common

Answer 7

as electrons are lost they become more strongly attracted to the nuclei so they are less likely to be involved in bonding

Question 8

why do Ti(4+) and Mn(7+) form the highest oxidation numbers

Answer 8

because all of their 4s and 3d electrons become involved in bonding

Question 9

why do ligands form with transition metals

Answer 9

transition metals have small atomic radius in comparison to other atoms in the same period therefor they attract electron-rich species more strongly allowing them to form bonds

Question 10

define ligand

Answer 10

a species that uses a lone pair of electrons to form a dative bond with a metal ion

Question 11

what is a ligand complex

Answer 11

a species containing a metal ion joined to ligands

Question 12

what is a complex ion

Answer 12

a ligand complex with an overall charge

Question 13

what is the coordination number

Answer 13

the number of dative bonds in the complex

Question 14

what are the 4 most common ligands and their names in a complex

Answer 14

water - aqua
hydroxide - hydroxo
ammonia - ammine
chloride - chloro

Question 15

what is the name of the complex [Fe(H2O)6]^2+

Answer 15

hexaaquairon(II)

Question 16

what is the name of the complex [FeCl4]-

Answer 16

tetrachloroferrate(III)

Question 17

when is the latin name for the metal used when naming complexes

Answer 17

if the ion is negative

Question 18

name the complex [Cu(NH3)4(H2O)2]^2+

Answer 18

tetraamminediaquacopper(II)

Question 19

why do transition metals form coloured ions and compounds

Answer 19

because when ligands attach to the metal the d energy levels splits into 2 different energy levels and when light energy is absorbed an electron from the lower energy level is exited/promoted to the higher energy level and the complementary colour of the frequency absorbed is transmitted

Question 20

what is the shape of a molecule that forms 6 ligands and its bond angle

Answer 20

octahedral
90

Question 21

what is the shape of a molecule that forms 4 ligands and its bond angle

Answer 21

tetrahedral
109.5

Question 22

what is the shape of a molecule that forms 2 ligands and its bond angle

Answer 22

linear
180

Question 23

what is six-fold coordination

Answer 23

complexes in which there are 6 ligands forming coordinate bonds with the transition metal

Question 24

what is the colour of hexaaquamanganese(II) [Mn(H2O)6]2+

Answer 24

very pale pink (usually seen as colourless)

Question 25

what is the colour of tetraaquadihdryoxoiron(II) [Fe(H2O)4(OH)2)

Answer 25

pale green

Question 26

what is the colour of hexahydroxoaluminate(III) [Al(OH)6]^3-

Answer 26

colourless

Question 27

why do chlorine ligands often only form 4 coordinate bonds

Answer 27

because chlorine is a very large ion therefor there is not enough space around the central metal ion for 6

Question 28

what is the square planar shape

Answer 28

contains a central or ion surrounded by four atoms or ligands in the same plane with bond angles of 90

Question 29

why is cis-platin important

Answer 29

it is an effective treatment of cancer (especially testicular cancer)

Question 30

describe the structure of cis-platin

Answer 30

central platinum(II) ion 2 ammonia ligands facing each other and 2 chloride ligands facing each other

Question 31

summarise how cis-platin works

Answer 31

when cells divide the DNA must separate into 2 strands to be copied and cis-platin forms a bond between the 2 strands of DNA and prevents them from separating so the cancer cells can’t divide

Question 32

why is cis-platin used and not trans-platin

Answer 32

trans-platin is much less effective and more toxic

Question 33

what is a monodentate ligand

Answer 33

a ligand which forms one dative bond with a metal ion

Question 34

what is a bidentate ligand

Answer 34

a ligand that forms 2 dative bonds with a metal ion

Question 35

what is a multidentate ligand

Answer 35

a ligand that forms several dative bonds with a metal ion

Question 36

what is the most common bidentate ligand

Answer 36

1,2, diaminoethane (ethylenediamine)
NH2CH2CH2NH2

Question 37

how does the change from a monodentate ligand to a multidentate ligand effect the stability of the products

Answer 37

if 6 monodentate ligands are replaced by 1 multidentate ligand then there will be more species in the products therefor the system becomes more disordered which increases stability of the product

Question 38

what ion plays an important role in heamoglobin

Answer 38

Fe2+

Question 39

why is Fe2+ important in the haem group

Answer 39

oxygen uses one of it’s lone pairs to form a dative bond with an Fe2+ ion in the haem group

Question 40

why is carbon monoxide toxic (in terms of dative bonds)

Answer 40

carbon monoxide has a lone pair of electrons so it can act as a ligand and when it comes into contact with haemoglobin it forms a stronger dative bond than oxygen so the oxygen is substituted and the dative bond between carbon monoxide and haemoglobin becomes extremely hard to overcome