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CHEMISTRY A LEVEL > CHAPTER 24 - TRANSITION ELEMENTS > Flashcards

CHAPTER 24 - TRANSITION ELEMENTS Flashcards

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1
Q

Where are d block elements found on the periodic table

A

Between Group 2 and Group 13 (Scandium to Zinc)

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2
Q

What are the properties of d-block elements

A

High MP+BP
Shiny appearance
Conduct Electricity and Heat

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3
Q

What are some uses for d-block elements

A

Construction and tools (Fe)
cables and water pipes (Cu)
Aerospace and Joint replacement (Ti)
Coins (Cu, Ni, Zn)

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4
Q

What are the exceptions to electron configurations in d-block elements

A

Chromium and Copper

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5
Q

Why do Chromium and Copper not fulfil the normal electron configurations

A

Half filled d5 and fully filled d10 sub-shells are more stable

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6
Q

What are the general rules for formation of atoms and ions in d-block elements

A

When forming an atom, 4s orbital FILLS before the 3d orbitals

When forming an ion, 4s EMPTIES before 3d orbitals

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7
Q

What are transition elements

A

d-block elements that form at least one ion with a partially filled d-orbital

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8
Q

Which d-block elements are not classified as transition elements and why

A

Scandium and Zinc
Dont form at least one ion with a partially filled d-orbital

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9
Q

Properties of transition metals and their compounds

A

High MP+BP
Conduct Electricity and Heat
Variable oxidation states
Coloured compounds
Catalysts

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10
Q

Variable oxidation states and colours

A

Pg 402 - Table

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11
Q

What colours do the two most common oxidation states of iron and chromium each form when dissolved in water

A

Iron (II) - Pale green
Iron (III) - Yellow
Chromium (III) - Green
Chromium (VI) - Yellow/orange

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12
Q

How do Transition metals act as catalysts

A

Increases rate of reaction
Provides Alternative pathway
Lowers Ea
Remains chemically unchanged

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13
Q

Examples of transition metals as catalysts?

A

Haber Process - Iron
Contact Process - V2O5
Hydrogenation of Vegetable oils - Nickel
Decomposition of H2O2 - MnO2

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14
Q

What are Complex ions?

A

When one or more molecule or negatively charged ion(s) (ligands) bond to a central metal ion

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15
Q

What is a Ligand

A

A molecule or ion that donates a pair of electrons to a central metal ion to form a coordinate bond or a dative covalent bond

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16
Q

What is a Dative covalent/coordinate bond?

A

A covalent bond where one atom provides both of the electrons for the shared pair

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17
Q

What is a coordination number

A

Shows how many bond are attached to a central metal ion

18
Q

How are complex ions represented

A

Complex ion inside square brackets with charge on outside
eg. [Cr(H2O)6] 3+

19
Q

Name an uncharged ligand

A

Water

20
Q

What are monodentate ligands

A

Ligand able to donate one pair of electrons to a central ion
eg. H2O, NH3, Cl-, CN-, OH-

21
Q

What is a Bidentate ligand?

A

Ligand which can donate two lone pairs to the central metal ion, forming two coordinate bonds
eg. 1,2 diaminoethane and ethanedioate (pg 406)

22
Q

What shape do six-coordinate complexes form?

A

Octahedral
90 degree bond angle
2 bonds straight
2 bond into
2 bonds out of
(pg 407)

23
Q

What shapes do four-coordinate complexes form?

A

Tetrahedral
109.5 angle
2 straight
1 in and 1 out of

Square Planar
90 angle
2 in 2 out

24
Q

What are the stereoisomers in complex ions

A

Optical isomerism
Cis-trans isomerism

25
Q

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

A

Light blue to dark blue ppt

26
Q

What happens when Chloride ions are added to a solution of [Cu(H2O)6] 2+

A

Pale blue to yellow colour change - shape change from octahedral to tetrahedral

27
Q

What happens when aqueous ammonia is added to [Cr(H2O)6] 3+

A

grey-green to purple

28
Q

What happens when haemoglobin binds to oxygen

A

Fe2+ binds to oxygen gas, in the capillaries of the lungs

Forms Oxyhaemoglobin, which releases this oxygen to body cells when required

29
Q

What happens when carbon dioxide binds to haemoglobin

A

CO2 binds to Haemoglobin in RBCs

Released from the red blood cells and exhaled

30
Q

What happens when Carbon Monoxide binds to Haemoglobin

A

Binds to Fe2+, forming Carboxyhaemoglobin

If carbon monoxide is breathed in, a ligand substitution reaction takes place where the oxygen is replaced by Carbon monoxide, bonding more strongly

So a small amount of CO can cause large proportion of haemoglobin molecules carrying oxygen

Forms irreversible reaction, when concentration of carboxyhaemoglobin is too high, oxygen transport is prevented, leading to death.

31
Q

What makes a precipitate

A

When two aqueous solutions containing ions react together to form an insoluble ionic solid (ppt)

(usually Dissolvable in excess NaOH)

32
Q

What colours do Fe2+, Fe3+, Cu2+ and Mn2+ form when reacting with Aqueous NaOH

A

Fe(OH)2: Green, Orange-brown in air
Fe(OH)3: Orange-brown
Cu(OH)2: Blue (dissolves in excess NH3)
Mn(OH)2: Light-brown

33
Q

What colour ppt is formed when Chromium 3+ reacts with NaOH ions?

A

Green / Dark Green ppt
(dissolves with excess ammonia - forms new complex ion)

34
Q

How is Iron oxidised from Fe2+ to Fe3+?

A

MnO4- is reduced to Mn2-

Purple solution of MnO4- when iron is added turns colourless

35
Q

What happens when iron is reduced from Fe3+ to Fe2+

A

I- ions react with the Orange-brown Fe3+ ions are reduced to pale-green Fe2+ ions
I- is oxidised to I2

36
Q

What is the colour change from Cr2O7 2- to Cr3+ ions, the a further reduction to Cr2+ ions using excess Zinc

A

Orange to green

Then green to Pale Blue

37
Q

What oxidation state is chromium oxidised from Cr3+ to CrO4 2-

A

Cr3+ to Cr6+

3H2O2 + 2Cr3+ + 10OH- = 2CrO4 2- + 8H2O

38
Q

What is the equation when copper is oxidised and what colour change is seen

A

2Cu2+ + 4I- = 2CuI + I2
Pale blue - White Ppt + Brown solution

39
Q

How can you tell if ammonium ions have reacted with OH- ions?

A

Forms NH3 + H2O
Damp red indicator will turn blue if NH4+ ions are present

40
Q

What is the chemical test for carbonate ion and what is observed?

A

Add dilute HNO3, effervescence seen

41
Q

What is the chemical test for sulfate ion and what is observed?

A

Add Ba2+ ions , forms white ppt (BaSO4)

42
Q

What is the chemical test for Halide ions and what is observed?

A

Add Ag+ ions

Will form AgX

AgCl - white ppt in dilute NH3
AgBr - cream ppt in conc NH3
AgI - Yellow ppt - insoluble

CHEMISTRY A LEVEL (14 decks)

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