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A Level Chemistry (OCR B Salters) > Developing Metals > Flashcards

Flashcards in Developing Metals Deck (43):
1

What are transition metals?

d-block elements that form 1 or more stable ions with incompletely filled d-orbitals

2

What are the 2 main reasons why d-block elements have many features in common?

Have essentially the same outer electronic arrangement - nearly all have 4s2

Unlike other elemental groups don't differ by complete electronic group but only by 1 more e- in incomplete inner 3d sub-shell

3

What is the convention for writing out the order of electronic sub-shells?

Principle electron shells kept together

Means [Ar]3s23p63d104s2 even though 4s filled before 3d

(as is at a lower energy level)

4

What is the electronic configuration of an Iron(II) ion?

[Ar]3s23p63d6

5

What is the electronic configuration of an Iron(III) ion?

[Ar]3s23p63d5

6

What is the electronic configuaration of a Copper(I) ion?

[Ar]3s23p63d10

7

What is the electronic configuration of a Copper(II) ion?

[Ar]3s23p63d9

8

What colour is an aqueous Iron(II) ion?

Green

9

What colour is an aqueous Iron(III) ion?

Orange/Brown

10

What colour is an aqueous Copper(I) ion?

N/A

Doesn't form aquesous ions

(Due to disproportionation reaction - Cu + Cu2+ always formed instead)

11

What colour is an aqueous Copper(II) ion?

Blue

12

Why do Cr and Cu have odd electronic configurations?

In the ground state, e- are arranged to give the lowest total energy

In period 4, the energies of 3d + 4s orbials are very close together therefore causing odd configuartions

13

What is the electronic configuration of Cr and why is this?

[Ar]3s23p63d54s1

NOT 3d44s2

1e- in each 3d orbital + the 4s orbital

14

What is the electronic configuration of Cu and why is this?

[Ar]3s23p63d104s1

NOT 3d94s2

2e- in 4s would be higher energy than filling 3d subshell

15

What test can be used to identify Fe2+, Fe3+, and Cu2+ ions in solution and why?

Using NaOH(aq) as they all form precipitates

16

What is formed when NaOH(aq) is added to an Fe2+ solution?

Give the equation and colour of the precipitate

Iron(II) hydroxide - green precipitate

Fe2+(aq) + 2OH-(aq) → Fe(OH)2(s)

17

What is formed when NaOH(aq) is added to an Fe3+ solution?

Give the equation and colour of the precipitate

Iron(III) hydroxide - brown precipitate

Fe3+(aq) + 2OH-(aq) → Fe(OH)2(s)

18

What is formed when NaOH(aq) is added to an Cu2+ solution?

Give the equation and colour of the precipitate

Copper(II) hydroxide - pale blue precipitate

Cu2+(aq) + 2OH-(aq) → Fe(OH)2(s)

19

What reactions occur is ammonia is added to aqueous Fe2+, Fe3+, or Cu2+ ions?

Why?

The same reactions as when NaOH(aq) added - hydroxide precipitates formed

Because ammonia is also a source of OH- ions

20

What reaction occurs when excess ammonia is added to precipitate of Cu(OH)2?

Pale blue Cu(OH)2 precipitate dissolves to form deep blue solution of copper ammonia complex [Cu(NH3)(H2O)2]2+(aq)

21

How is the reaction of Cu2+ with excess ammonia different to those of Fe2+ and Fe3+?

Fe(OH)2 and Fe(OH)3 don't form complexes with ammonia

22

What is a complex?

A central metal atom surrounded by negative ions/neutral molecules posessing a long pair (ligands)

23

What is a ligand?

A negatively charged/neutral molecular with a lone pair of electrons, surrounding a transition metal/ion.

Attached to metal by dative covalent bonds

24

Define co-ordination number

The number of bonds from the central metal atom/ion (in a compex) to ligands.

NOT necessarily the number of ligands! (e.g. is bi/polydentate)

25

What is a complex ion?

Transition metal surrounded by a number of ligands

26

What is a monodentate ligand?

Ligand that attaches to a transition metal through 1 atom only

27

What is a bidentate ligand?

A ligand with 2 long pairs/negative charges that forms 2 bonds to a metal atom/ion

28

What is a polydentate ligand?

A ligand that forms several bonds to a metal atom/ion and has several lone pairs/areas of negative charge

29

What is a chelate ring?

A many-membered ring that forms when a bi/polydentate ligand bonds to a metal.

30

What type of ligand is an ethanedioate ion?

What is its chemical formula?

A bidentate ligand

-OOC-COO-

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31

What is a ligand substitution reaction?

When one ligand replaces another in a complex

32

What is necessary for a ligand substitution reaction to occur?

What can be used to determine whether it will occur or not?

Will only occur if the new complex is more stable than the old, therefore the stability of the complex depends on its ligands

If the Kstab value is higher for the new ligand then substitution will occur

33

What shape and colour is a [Cu(H2O)6]2+ complex?

Blue

Octahedral

34

What are the two possible ligand substitution reactions for a [Cu(H2O)6]2+ ion?

What colour + shape are the complexes formed?

[CuCl4] Tetrahedral + Yellow

[Cu(NH3)4(H2O)2]2+ Octahedral + Deep blue/violet

35

What are the four possible shapes a compex ion can be?

Linear

Square planar

Tetrahedral

Octahedral

36

What does a linear complex ion look like + what are its co-ordination number and bond angles?

Co-ordination no = 2

Bond angles = 180º

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37

What does a square planar complex ion look like + what are its co-ordination number and bond angles?

Co-ordination no = 4

Bond angles = 90º

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38

What does a tetrahedral complex ion look like + what are its co-ordination number and bond angles?

Co-ordination number = 4

Bond angles = 109.5º

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39

What does a octahredral complex ion look like + what are its co-ordination number and bond angles?

Co-ordination no = 6

Bond angles = 90º

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40

What does the presence of ligands cause the d sub-shell to do?

Split into higher + lower energy levels

41

Why are d-block complex ions coloured?

The presence of ligands causes the d sub-shell to split into higher + lower energy levels

When visible light is absorbed, e- can be excited to a higher energy level.

The frequency of light absorbed is proportional to the gap between energy levels -ΔE = hv

The complimentary colour is transmitted and is the colour we observe

42

What factors affect the gap between energy levels of ligands?

In other words, why are metal complexes different colours?

Number of e- present in metal (i.e what metal/oxidation state)

Arrangement of ligands around ion as this affects splitting of d-shell

Nature of ligand - differone ones have different effects on relative energies of d-orbitals in a particular ion

43

What technique can be used to find the concentration of a coloured solution?

Why?

Colorimetry

Because absorbance is proportional to concentration

Therefore greater absorbtion = greater concentration