Ocr Chemistry Unit 2: Module 3 - Transition Elements

Front 1

Transition elements (properties)

Define transition element

Back 1

A d-block element that forms an ion with an incomplete d subshell

Front 2

Transition elements (properties)

Why are Scandium and Zinc not transition elements?

Back 2

They do not form ions with incomplete d-sub shells

Sc forms Sc 3+ - in which d-orbitals are empty

Zn forms Zn 2+ - in which d-orbitals are full

Front 3

Transition elements (properties)

Draw the diagram cheat thing for the energy levels of orbitals (Aufbau principle)

Back 3

Front 4

Transition elements (properties)

How do Chromium and Copper differ from other transition elements?

Back 4

They do not follow the Aufbau principle:

Chromium - the 3d and 4s orbitals all contain one electron with no orbital completely filled

Copper - the 3d orbitals are full, but there is only one electron in the 4s orbital

Front 5

Transition elements (properties)

Draw the entire electronic configurations for transition elements.

Back 5

Front 6

Transition elements (properties)

Why do Copper and Chromium not follow this pattern?

Back 6

electron repulsions between the outer electrons are minimised, resulting in increased stability of the atoms

Front 7

Transition elements (properties)

In their reactions, transition element atoms...

Back 7

lose ions to form positive ions.

Front 8

Transition elements (properties)

Where are electrons lost from first?

Back 8

4s electrons are lost first despite them being filled first because once occupied, 4s electrons have a higher energy level.

Front 9

Transition elements (properties)

Describe the physical properties of transition metals.

Back 9

Normal metallic properties: shiny, high densities, high melting points and high boiling points.

When solid, they exist as giant metallic lattices containing delocalised electrons which move to conduct electricity.

Front 10

Transition elements (properties)

Use of Ni?

Back 10

Alloyed with copper for use in making 'silver' coins

Front 11

Transition elements (properties)

Use of titanium

Back 11

Component for joint replacement parts - ball + socket for hip replacement

Front 12

Transition elements (properties)

Use of Iron?

Back 12

Cast to make telephone boxes and post boxes, or alloyed for use in the construction of buildings and bridges.

Front 13

Transition elements (properties)

What do transition elements form?

Back 13

Compounds in which the transition metal has different oxidation states.

Front 14

Transition elements (properties)

What do transition element compounds form? and often do?

Back 14

Coloured solutions when dissolved in water , they often catalyse chemical reactions.

Front 15

Transition elements (properties)

The transition elements all form compounds...

Back 15

with ions in a +2 oxidation state by the loss of two electrons in the 4s orbital.

Front 16

Transition elements (properties)

Why are 4s electrons lost first?

Back 16

When electrons occupy the 4s orbital it has a higher energy level.

Front 17

Transition elements (properties)

What do strong oxidising agents often contain?

Give two examples.

Back 17

The highest oxidation state of a transition element.

Manganese forms potassium permanganate, KMnO4, a purple solid used as an oxidising agent in redox titrations. Mn - 7+
Chromium is found in potassium dichromate, K2Cr2O7, an orange crystalline solid that acts as an oxidising agent in the preparation of aldehydes and ketones from alcohols. Cr - 6+

Front 18

Transition elements (properties)

How are transition metal ions coloured?

Back 18

When white light passes through a solution containing transition metal ions, some of the wavelengths of visible light are absorbed. The colour we observe is a mixture of the wavelengths of light that are not absorbed.

Front 19

Transition elements (properties)

Describe the colour of Copper (II) sulfate

Back 19

Appears pale blue because the solution absorbs the red/orange region of the electromagnetic spectrum and reflects/transmits the blue.

Front 20

Transition elements (properties)

What is colour in organic chemistry linked to?

Back 20

The partially filled d-orbitals of transition metal ions.

Front 21

Transition elements (properties)

Describe the colour of Scandium(III). Include the electronic configuration.,

Back 21

No colour - there are no partially filled d-orbitals.

1s2 2s2 2p6 3s2 3p6

Front 22

Transition elements (properties)

Define catalyst

Back 22

A substance that increases the rate of a chemical reaction by providing an alternative route for the reaction to follow with lower activation energy.

Front 23

Transition elements (properties)

Why do transition metals act as catalysts?

Back 23

1) Transition metals provide a surface on which a reaction can take place. Reactants are adsorbed onto the surface of the metal and held in place while a reaction occurs. After the reaction, the products are desorbed and the metal remains unchanged.

2) Transition metal ions have the ability to change oxidation states by gaining or losing electrons. They bind to reactants forming intermediates as part of a chemical pathway with lower activation energy.

Front 24

Transition elements (properties)

What are the four processes catalysed by transition metals ?

Back 24

1) Haber process

2) Contact process

3) Hydrogenation of alkenes

4) Decomposition of Hydrogen Peroxide

Front 25

Transition elements (properties)

Describe the Haber process. Include catalyst and catalyst function.

Back 25

Used to make ammonia, NH3, from N2 and H2.

N2 (g) + 3H2 (g) <---> 2NH3(g)

Catalyst: Iron metal. Increases rate, lowers temp at which reaction takes place.

Front 26

Transition elements (properties)

Describe the Contact process. Include the catalyst

Back 26

Used to convert SO2 sulfur dioxide into SO3 sulfur trioxide, (for the manufacture of H2SO4)

2SO2 (g) + O2 (g) <---> 2SO3(g)

Catalyst : Vanadium(V) oxide, V2O5 = +5

H2SO4 is an important inorganic chemical with many uses: production of...

-fertilisers

-detergents

-adhesives and explosives

-electrolyte in car batteries

Front 27

Transition elements (properties)

Describe hydrogenation of alkenes. Include catalyst.

Back 27

Hydrogen is added across the C=C double bonds in unsaturated compounds to form saturated compounds - this is HYDROGENATION.

C2H4 + H2 ---> C2H6

Catalyst: Ni - lowers temp and pressure required.

- Used in the hydration of unsaturated vegetable oils to make spreadable margarine

Front 28

Transition elements (properties)

Describe the decomposition of hydrogen perocide.

Back 28

Hydrogen peroxide decomposes slowly at room temperature and pressure into H2O and O2. A catalyst is added to increase reaction rate.

2H2O2 (g) ---> 2H2O (l) + O2 (g)

Catalyst: Manganese(IV) oxide, MnO2 = +4.

Used to produce O2 (g)

Front 29

Transition elements (precipitation reactions)

What is a precipitation reaction?

Back 29

A reaction in which soluble ions in separate solutions are mixed together to produce an insoluble compound which settles out of solution as a solid (this is the ppt)

Front 30

Transition elements (precipitation reactions)

How do transition metal ions in aqueous solution form precipitates?

Back 30

Transition metal ions in aqueous solution react with aq NaOH to form coloured precipitates.

Front 31

Transition elements (precipitation reactions)

Draw a table to show the reactions of Cu2+, Co2+, Fe2+ and Fe3+ with aq NaOH. Include relevant equations, and colour change that occurs.

Back 31

Front 32

Transition elements (ligands and complex ions)

Back 32

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