Chemistry- Transition Metals

Front 1

Definition of a transition metal

Back 1

Is a d-block element that has an incomplete d-subshell as a stable ion

Front 2

What two metals are not classed as transition metals and why?

Back 2

Scandium- forms only sc3+ ion, in which the d orbitals are empty

Zinc- only form zn2+ ion, in which the d-orbitals are full

Front 3

What two transition metals do not follow the regular electron pattern and why?

Back 3

Chromium- the five 3d orbitals and the 4s orbital all contain one electron, with no obital being filled

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

Front 4

Why do transiton metals lose electrons from their 4s orbital before 3d?

Back 4

The 3d and 4s energy levels are very close together and, once electrons occupy the orbitals, the 4s electrons have a higher energy and are lost first

Front 5

Physical properties of transition metals?

Back 5

-lustrous in appearance

-high density

-high melting and boiling point

-when solid exist as giant metallic lattices, containing delocalised electrons, which move freely to conduct electricity

Front 6

Chemical properties of transition metals

Back 6

-have different oxidation states

-form coloured compounds when dissolved in water

-catalyse chemical reactions

Front 7

What colour is potassium dictomate and what is it used for?

Back 7

Orange crysallime solid

Acts as an oxidising agent in preparation of aldehydes and ketones from alcohols

Front 8

What is disproportionation reaction?

Back 8

Both species oxidised and reduced in the same chemical reaction

Eg. Copper oxide is reacted with hot dilute sulfuric acid , a brown precipitate of copper and blue solution of copper sulfate are formed

Front 9

How do transition metals obtain their colour?

Back 9

When white light passes through the solution, some of wavelengths of visible light are absorbed. The folour that we observe is a mixture of the wavelengths of the light that have not been absorbed.

Eg. Copper sulfate appears pale blue, because the solution absords red/orange but reflects blue

Front 10

How do transition metals work as catalysts?

Back 10

1) provide a surface on which the reaction can take place. Reactants ae absorbed onto the surface of the metal and held in place while the reaction occurs. Afte the reaction, the products are deabsorbed and the metal remains unchanged.

2) transition metals can change oxidation state by gaining and losing electrons. They bind to the reactants, formijg intermediates as part of a chemical pathway, ofter with a lowet activation energy, which speed up the reaction

Front 11

Advantages and disadvantages of using transition metals in industry

Back 11

Advantages: inprove profits by reducing time it takes to make the product and reduce the amount if energy needed to make the reaction occur

Disadvantage: can be toxic. When substances bring to the active site and stop the transition metals from working, the catalyst can no longer be used. It must be disposed of in a way not to cause harm or pollution.

Front 12

Examples of transition metal catalysts in industry?

Back 12

Haber process: iron catalyst

Contact process: vandium oxide catalyst

Hydrogenation of alkenes: nickel catalyst

Decompositon of hydrogen peroxide manganese oxide

Hydrogen production: coppersulfate catalyst

Front 13

Definition of complex ion

Back 13

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

Front 14

Definition of ligand

Back 14

A molecule or ion that can donate a lone pair of electrons to the transition metal ion to form a coordinate bond

Front 15

Coordination number

Back 15

Is the total number of coordinste bonds formed between a central metal ion and its ligands

Front 16

What are Monodentate ligand and examples

Back 16

Ligand only donates just one pair of electrons to the central metal ion to form one coordinate bond

Front 17

What are bidentate ligands? And example

Back 17

Have two pair of electrons from different atoms to donate to the central metal. This means two coordinate bonds can be formed.

Eg. NH3CH2CH2NH2 'en'

Front 18

What is a hexadentate ligand? And example- what is its purpose

Back 18

Hexadentate ligands has 6 lone pairs of electrons available to form coordinate bonds.

Eg EDTA^ 4-

EDTA is used to bind metal iond and is known as a chelating agent. This means it decreases the concentration of the metal ions in solutions by binding them into the complex.

Front 19

What are 6 fold coordination called? What do they look like? Angles?

Back 19

Octahedral. All bond angles as 90 or 180 degree. Coordination number is 6

Front 20

Four-fold coordination shapes? And details of them

Back 20

Tetrahedral- chlorine ligands are so large that only four can fit around a transition metal

Square planar- eg cis platin

Front 21

Definition of stereoisomer?

Back 21

Species with the same structural formula but with a different arrangement of the atoms in soace

Front 22

What two isomers did alfred werner discover? What colour were they?

Back 22

(Co(NH3)4Cl2)

Cis-purple

Trans-green

Front 23

Isomerism in four coordinate complex? Example?

Back 23

Front 24

How is transition metal complexes used in medicine? Eg cis platin

Back 24

Cis platin is used as treatment ( chemotherapy) for cancer.

Cells divide to make more cells of the same type. Cancer is spread through an organism by cell division of cancerous cell that can reproduce itself

Cis-platin binds to the DNA of fast growing cancer cells. This prevents cell division. Activation of the cells repair mechanism eventually leads to the death of the cancer comtaining cell.

But carboplatin as been developed- used for ovarian cancer. Lower dose and fewer side effects.

Front 25

Structure of bidentate ligand- ethanedioate ligand

Back 25

Front 26

Cis- trans isomers of 2 monodentate and 2 bidentate ligands

Back 26

Front 27

What are optical isomers and examples?

Back 27

Optical isomers are non- superimpossible mirror images of each other

Requirements:

- 3 bidentate ligands (Ni(en)3)2+

-2 bidentate and 2 monodentate (co(en)2Cl2)

-one hexadentate ligand eg (cu(EDTA))2-

Front 28

Definition of ligand substitution

Back 28

Is a reaction in which one ligand in a complex ion is replaced by another ligand

Front 29

Colour change and equation for aqueous copper (ii) ions and ammonia

Back 29

Small amount of ammonia:

Pale blue --> pale blue precipitate formed

Excess ammonia --> pale blue precipitare dissolve and deep blue solution forms.

Hint 29

Front 30

Copper (ii) ions and hydrochloric acid equation and colour change

Back 30

Concentrate hydrochloric acid is added to aqueous copper ions:

Pale blue --> yellow --> green

Can be reversed by adding water

Front 31

Why do complexes only fit 4 chlorine ligands

Back 31

Chlorine ions are larger than water ligands and have stronger replusions, so fewer chlorine ligands can fit around the central metal ion. Has a tetrahedral shape.

Front 32

Products/ colour and equation of the reaction of chromium (iii) and ammonia

Back 32

Dark green--> green precipitate

When a small amount of ammonia is added hydrogen ions are pulled off the water ligands.

When excess ( concentrated) ammonia is added, some of the green precipitate re-dissolves to form a dark green solution.

All ligands are replaced by ammonia

Front 33

Role of haemoglobin

Back 33

Contains iron haem group

Oxygen can bind to this.

As blood passes theough the lungs, the haemoglobin picks up oxygen and carries itto every living cell, where it can be released.

Front 34

Structure of haemoglobin and its bonding

Back 34

4 coordinate bonds between Fe2+ and nitrogen

One bond between globin and fe2+

One bond between oxygen and fe2+

Front 35

Carbon monoxide as an example for ligand substitution in haemoglobin

And symptoms

Back 35

Leaves fewer haemoglobin molecules to bind to oxygen molecules. Tissues can be starved of oxygen.

Reaction is not reversible.

Symptoms include headaches nausea and pottential suffocation. Can be fatal.

Front 36

When is carbon monoxide formed? How can we detect it?

Back 36

Incomplete combustion of carbon containing fuels.

Burning tobacco- why smokes become short of breath

Its odourless and colourless

Sensors like smoke detectors.

Front 37

Colour change and equation: Cu2+ and NaOH/ NH3

Back 37

NaOH: blue to blue gelatinous precipitate

NH3: blue to blue geletinous precipitate which redissolves to blue solution

Front 38

Colour change and equation of Fe2+ and NaOH/NH3

Back 38

Naoh: pale green to green precipitate tunring rusty brown at its surface standing in air

Nh3: pale green to dark green precipitate

Front 39

Colour change and reaction of Fe3+ and naoh / nh3

Back 39

Naoh: pale yellow to rust brown precipitate

Nh3: pale yellow to rusty brown precipitate

Front 40

Colour change and equation mn2+ and nh3/naoh

Back 40

Naoh: pale pink to brown precipitate that darkens in the air as it oxidises

Nh3: brown precipitate

Front 41

Colour change and reaction of cr3+ and naoh/ nh3

Back 41

Naoh: green to green precipitate

Nh3: green precipitate which redissolves if excess ammonia is added

Front 42

What does a redox reaction involve?

Back 42

The transfer of electrons from one species to another

Oxidising agent can be titratwd against reducing agent

Front 43

How does a titration involving manganate ions work?

Back 43

Used to oxidise Fe2+ ions. The solution is acidified with sulfuric acid. Hcl cannot be used as it reacts with mno4-. It is unsafe because chlorine gas is formed.

Mn04 is in th3 burette.

Iron 2+ in the connical flask eith sulfuric acid

Front 44

Pottasium dicromate and Fe2+ ions colour and equation

Back 44

Colour change is very subtle. Indicator is used which produces a violent- blue coloured point

Front 45

Iodine ane thiosulfate equation and reaction

Back 45

Forms tetrathionate ion

Front 46

Copper and iodine titration colour change and reaction and then titrated against sodium thiosulfate

Back 46

Poduces light brown/ yellow solution and white precipitate of copper iodide

When titrated agains sodium thiosulfate , becomes paler.

Starch is added as a indicator.

Front 47

Positive ions- testing for ammonia ions

Back 47

Ammonia ion reacted eith hydroxide ions.

Add sodium hydroxide and warm gently.

Distinctive smell gass turns red litmus paper blue.

Front 48

Negative ions- testing for carbonate ions

Back 48

Add stong acid eg hcl

Collect any bubbles or gas and pass through limewater.

Limewater turns cloudy.

Front 49

Negative ions- testing for sulfate ions

Back 49

Add dilute hydrochloric acid barium chloride. White precipitate is formed.

Front 50

Negative ions- testing for halide ions

Back 50

Dissolve suspected halide in water if not in aqueous form

Add dilute nitric acid and aqueous silver nitrate

Chloride ions- white precipitate

Soluble in dilute nh3

Bromide ions- cream precipitate

Soluble in concentrated nh3

Iodide ions- yellow precipitate

Insoluble in both nh3