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CheMisTry - Developing Metals > DM.1 > Flashcards

DM.1 Flashcards

Introduction to transition metals and their oxidation states

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1
Q

Why are d-block elements so different to elements from other parts of the periodic table?

A

They have special electronic configurations and energy levels associated with their electrons, giving them special properties.

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2
Q

What would you say about the differences between elements within a group in the d-block compare to other parts of the periodic table?

A

They are less apparent compare to other parts of the periodic table like group 1 and 2.

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3
Q

What would you say about the similarities between elements across a period in the d-block compare to other parts of the periodic table?

A

There are greater similarties across a period between elements.

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4
Q

What is the electron configuration of scandium, Sc, representing core electron configuration with [Ar]?

A

[Ar]3d1 4s2

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5
Q

What is the electron configuration of titanium, Ti, representing core electron configuration with [Ar]?

A

[Ar]3d2 4s2

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6
Q

What is the electron configuration of vanadium, V, representing core electron configuration with [Ar]?

A

[Ar]3d3 4s2

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7
Q

What is the electron configuration of chromiun, Cr, representing core electron configuration with [Ar]?

A

[Ar] 3d5 4s1

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8
Q

What is the electron configuration of manganese, Mn, representing core electron configuration with [Ar]?

A

[Ar]3d5 4s2

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9
Q

What is the electron configuration of iron, Fe, representing core electron configuration with [Ar]?

A

[Ar]3d6 4s2

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10
Q

What is the electron configuration of cobalt, Co, representing core electron configuration with [Ar]?

A

[Ar]3d7 4s2

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11
Q

What is the electron configuration of nickel, Ni, representing core electron configuration with [Ar]?

A

[Ar]3d8 4s2

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12
Q

What is the electron configuration of copper, Cu, representing core electron configuration with [Ar]?

A

[Ar]3d10 4s1

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13
Q

What is the electron configuration of zinc, Zn, representing core electron configuration with [Ar]?

A

[Ar]3d10 4s2

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14
Q

Why are electrons arranged in the way shown in the electronic configuration when the atom is in its ground state?

A

Because the electronic arrangement would give the lowest total energy, making it more stable.

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15
Q

Because electrons repel each other, what kind of orbiting arrangement would give the lowest total energy?

A

When electrons orbit singly in their orbitals than if they are paired up.

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16
Q

Why does chromium’s electron configuration not fit with the predicted pattern of adding one electron to the d orbital everytime?

A

This is because having the six electrons all singly in orbitals give a lower energy arrangement. By moving one electron from the s orbital to the d orbital avoids having pairs of electrons in the same orbital.

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17
Q

Similarly, why does copper’s electron configuration not fit with the pattern?

A

The 3d orbitals are at lower energy than the 4s orbitals therefore the lowest total energy would be when all the electron pairs are in the d orbitals rather than having one in the s orbital.

18
Q

Which electrons are always lost first when ions of transition metals are formed?

A

The 4s electrons.

19
Q

What is the definition of a transition metal?

A

D-block elements that can form one or more stable ions with incompletely filled/partially filled d-orbitals.

20
Q

What is the relationship between d-block elements and transition metals?

A

All transition metals are d-block elements, but not all d-block elements are transtion metals.

21
Q

Which elements from the first row of d-block elements are not classes as transition metals?

A

Scandium and zinc.

22
Q

Which columns of the d-block contain elements that are not classed as transtion metals?

A

The first column and the last column.

23
Q

Why is scandium not classed as a transition metal?

A

Scandium only forms Sc3+ ions, and the electron configuration of this ion has an empty d-orbital.

24
Q

The Sc3+ ion behaves similarly to which element?

A

Aluminium

25
Q

Why is zinc not classed as a transition metal?

A

Zinc only forms Zn2+ ions, and the electron configuration of this ion has a filled 3d orbital.

26
Q

The Zn2+ behaves similarly to which group of elements?

A

Group 2.

27
Q

What are four signiture properties of transition metals?

A
  1. Variable oxidation states
  2. Catalyst activity
  3. Coloured compounds
  4. Complex formation
28
Q

Why can transition metals exist in a number of oxidation states?

A

Because there are several stable arrangements of the d electrons and s electrons.

29
Q

What method can be used to analyse the iron content in solution using the ideas of transition metal variable oxidation states?

A

Redox titration.

30
Q

What oxidising agent is used in the redox titration to find the concentration of iron in a solution?

A

Manganate(VII) ions, which can be found in potassium manganate(VII) solution.

31
Q

What condition should the redox titration be carried out in and why?

A

Acidic conditions, it provides the H+ ions needed to reduce the oxidising agent.

32
Q

What colour is manganate(VII) ion?

A

Purple

33
Q

What is the half equation that shows iron(II) being oxidised?

A

Fe2+(aq) → Fe3+(aq) +e-

34
Q

What is the half equation that shows manganate(VII) being reduced?

A

MnO4-(aq) + 8H+(aq) +5e- → Mn2+(aq) + 4H2O(l)

35
Q

Why is manganate(VII) ion a good oxidising agent?

A

Because the oxidisation state of manganate is +7, the highest oxidising state, and therefore can be very easily reduced.

36
Q

What acid should be used in the redox titration?

A

Sulfuric acid. Do not use hydrochloric acid, because chloride ions are easily oxdised and chlorine gas can be produced.

37
Q

What would be observed at the end point and what does it imply?

A

When a pink colour persists in the previously colourless solution, this indicates that mangante(VII) ions are in excess.

38
Q

Desribe the method of the redox titration to find the concentration of iron in a solution?

A
  1. Put the standard MnO4- solution in the burette.
  2. Use a volumetric pipette to transfer the solution containing iron to a conical flask.
  3. Add excess H2SO4 to the flask.
  4. Titrate until a faint pink colour persist due to excess MnO4-.
  5. Repeat titration until you get concordant results.
39
Q

Why is an indicator not required for redox titration with MnO4-?

A

Because MnO4- ions have a purple colour which would be observed.

40
Q

What is another oxidising agent you could use instead of manganate(VII) to find iron concentration?

A

Dichromate(VI) ion, which has an orange colour.

CheMisTry - Developing Metals (6 decks)

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