5.3.1 - Transition Elements Flashcards Preview

A2 Chemistry > 5.3.1 - Transition Elements > Flashcards

Flashcards in 5.3.1 - Transition Elements Deck (81):
1

What is a transition element?

A d-block element that has at least one stable ion with an incomplete d subshell.

2

What are the exceptions when doing electron configuration?

Chromium and copper.

3

What is the electron configuration of chromium?

[Ar]3d5 4s1

4

What is the electron configuration of copper?

[Ar] 3d10 4s1

5

Why is the electron configuration different for copper and chromium?

The 4s subshell and 3d subshell are very close in energy. Therefore there is only one electron in the 4s subshell. This reduces electron repulsions and gives chromium extra stability from a half filled 3d subshell and copper extra stability from a full 3d subshell.

6

Where are electrons lost from when forming ions?

Lost from the 4s first, then the 3d.

7

Why are ions formed this way?

The 3d and 4s subshells are close in energy and once they are occupied, repulsion between the electrons causes the 4s subshell to have a higher energy than the 3d.

8

Why are scandium and zinc not transition elements?

They form ions without an incomplete subshell.

9

What are the properties of transition metals?

They exist in more than one oxidation state. They form coloured solutions when dissolved in water, they frequently catalyse chemical reactions.

10

Fe2+

Green

11

Fe3+

Brown

12

Mn2+

Pale pink

13

Mn7+

Purple

14

Cu2+

Blue

15

Cr2+

Blue

16

Cr3+

Green

17

Cr6+

Orange

18

Ni2+

Green

19

Examples of when transition metals catalyse reactions?

Iron in the Haber process, nickel in hydrogenation of C=C bonds, vanadium (V) oxide in the contact process.

20

Complex ion?

A central transition metal ion bonded to one or more ligands by coordinate bonds.

21

Ligand?

An ion or molecule with a lone pair of electrons that can be donated to a transition metal to form a coordinate bond.

22

Coordinate number?

The total number of coordinate bonds between a central metal ion and its ligand.

23

Monodentate ligand?

A ligand that donates one pair of electrons to the central metal ion.

24

Water as a monodentate ligand?

:OH2 no charge

25

Ammonia as a monodentate ligand?

:NH3 no charge

26

Thiocynate as a monodentate ligand?

:SCN- -1

27

Cyanide as a monodentate ligand?

:CN- -1

28

Chloride as a monodentate ligand?

:Cl- -1

29

Hydroxide as a monodentate ligand?

:OH- -1

30

What is a bidentate ligand?

One that donates two pairs of electrons to the central transition metal ion forming 2 coordinate bonds.

31

What is the name and bond angle of a complex ions with 6 coordinate bonds?

Octahedral 90 degrees.

32

What is the name and bond angle of a complex ion with 4 coordinate bonds?

Tetrahedral 109.5, square planar 90 degrees.

33

Which complex ions are usually square planar?

Nickel, palladium and platinum.

34

What is stereoisomerism?

Same molecular and structural formula, but different arrangement of atoms in space.

35

What are the bond angles in cis and trans?

Cis - 90, trans 180

36

What is optical isomerism?

When there is a different arrangement of the ligands in space which gives non-superimposable mirror images that rotate plane polarised by equal amounts in opposite directions.

37

What is cis Platin and what is it used for?

The cis isomer of platin. It is used as an anti cancer drug which binds to DNA in cancer cells and prevents cell division.

38

What is formed when any copper salt is dissolved in water?

The hexaaquo complex [Cu(H2O)6]2+

39

Write the equation for the reaction between chloride ions and the hexaaquo complex of copper.

[Cu(H20)6]2+ + 4Cl (reversible sign) [CuCl4]2- + 6H20

40

What colour is [Cu(H2O)6]2+

Blue solution

41

What colour is [CuCl4]2-

Yellow solution

42

Write the equation for the reaction between the hexaaquo complex of copper and ammonia.

[Cu(H2O)6]2+ + 4NH3 -> [Cu(NH3)4 (H2O)2]2+ + 4H2O

43

What is the colour of [Cu(NH3)4 (H2O)2]2+ and what is interesting about its shape?

Deep blue solution. Distorted octahedral shape due to longer H2O bonds.

44

What happens when ammonia solution is added dropwise to [Cu(H2O)6]2+

A pale blue precipitate of copper hydroxide is formed first which then dissolved in excess ammonia to form a deep blue solution. The ammonia is able to act as a base (removing a proton from the water) and a ligand (using its lone pair)

45

What is the hexaaquo complex of chromium?

[Cr(H2O)6]3+

46

What is the equation for when the hexaaquo complex of chromium is added to ammonia?

[Cr(H2O)6]3+ + 6NH3 -> [Cr(NH3)6]3+ + 6H2O

47

What colour is [Cr(H2O)6]3+

Green solution is sulphate ions present, violet if not.

48

What colour is [Cr(NH3)6]3+

Purple solution.

49

What happens when ammonia solution is added dropwise to the hexaaquo complex of chromium?

A grey green precipitate of chromium hydroxide is formed first which then dissolves in excess ammonia to form a purple solution.

50

What happens to Cu2+ when NaOH is added?

Blue precipitate.

51

What happens when NH3 is added to Cu2+?

Blue precipitate

52

What happens when excess NH3 is added to Cu2+?

Dissolves to deep blue solution.

53

What happens when NaOH is added to Fe2+?

Green precipitate which oxides to orange/brown.

54

What happens when NH3 is added to Fe2+?

Green precipitate which turns rusty brown due to oxidation.

55

What happens when NaOH is added to Fe3+?

Rusty brown precipitate.

56

What happens when NH3 is added to Fe3+?

Rusty brown precipitate

57

What happens to Mn2+ when NaOH is added?

Light brown precipitate which turns dark brown due to oxidation.

58

What happens to Mn2+ when NH3 is added?

Light brown precipitate which turns dark brown due to oxidation.

59

What happens when NaOH is added to Cr3+?

Green precipitate

60

What happens when XS NaOH is added to Cr3+?

The precipitate dissolves back to a green solution.

61

What happens when NH3 is added to Cr3+?

Green precipitate

62

What happens when XS NH3 is added to Cr3+?

Precipitate dissolves to green solution.

63

What is the half equation of Cu2+ reaction with NaOH?

Cu2+ + 2OH- -> Cu(OH)2

64

What is the half equation for Fe3+ reacting with NaOH?

Fe3+ + 3OH- -> Fe(OH)3

65

MnO4-

Purple

66

I-

Colourless

67

I2

Red brown

68

Cr2O7-

Orange

69

Zn

Grey solid

70

Zn2+

Colourless

71

H2O2

Colourless

72

O2

Gas

73

H2O

Colourless

74

What is equation for the reduction of Cu by I-?

2Cu+ + 4I- -> 2CuI + I2

75

What is CuI

White precipitate

76

What is I2 aqueous

Red brown solution

77

What is the equation for the disproportionation of Cu?

2Cu+ -> Cu + Cu2+

78

What does haemoglobin contain?

Fe2+ ions which form 6 coordinate bonds. Four of the lone pairs come from nitrogen atoms, and the fifth comes from a nitrogen atom on a protein (globin)

79

What happens in the lungs with haemoglobin?

The oxygen concentration is high so the water ligand is substituted for an oxygen molecule forming oxyhemoglobin.

80

What happens if carbon monoxide is inhaled?

The haemoglobin swaps its water ligand for a carbon monoxide ligand forming carboxyhaemoglobin.

81

Why is it bad when carboxyhaemoglobin is formed?

The CO is a strong ligand and doesn’t readily exchange with oxygen or water ligands, meaning the haemoglobin cannot transport oxygen anymore.