M5 Chapter 24 - Transition Elements pt1

Question 1

Define a transition element.

Answer 1

A d block element that forms at least one stable ion with partially filled d subshell.

Question 2

Where are the transition metals located in the periodic table?

Answer 2

In the middle block from Ti to Cu.

Question 3

What are the 2 elements in d block that are not considered as transition metals.

Answer 3

Scandium and Zinc

Question 4

Why is Scandium and Zinc not classified as transition metals?

Answer 4

Scandium only forms Sc3+, where the d orbitals are empty.
Zinc only forms Zn2+ where the d orbitals are full.

Question 5

What is the noble gas configuration of chromium?

Answer 5

[Ar]4s13d5

Question 6

What is the noble gas configuration of copper?

Answer 6

[Ar]4s13d10

Question 7

Which electrons do transition metals lose first when forming ions?

Answer 7

4s

Question 8

What are some characteristic physical properties of transition metals?

Answer 8

• Metallic
• High density
• High melting and boiling point
• Shiny
• Good conductors of heat and electricity

Question 9

What are the characteristic chemical properties of transition metals (4)?

Answer 9

• Variable oxidation states = take part in many redox reactions.
• Coloured compounds/ions in solution.
• Good catalysts.
• Form complex ions.

Question 10

In potassium manganate (VII), what is the oxidation number of Mn?

Answer 10

Mn = +7

Question 11

What are the two main ways in which transition metals act as an effective catalyst?

Answer 11

• Provide surface for reaction to occur
• They change oxidation states to form intermediates required for pathways with lower activation energy.

Question 12

Give some examples of transition metal catalysts and the processes/reactions they catalyse (4)?

Answer 12

Iron = Haber process
Vanadium (V) Oxide = contact process
Nickel = Hydrogenation of alkenes
Manganese (IV) oxide = decomposition of hydrogen peroxide.
Copper sulfate = Hydrogen production

Question 13

What is a complex ion?

Answer 13

Transition metal ion bonded to one or more ligands via coordinate bonds.

Question 14

Define a ligand.

Answer 14

Molecule or an ion that can donate a pair of electrons to the metal to form a coordinate bond.

Question 15

What is a coordinate bond?

Answer 15

A bond in which one of the atom provides both the electrons required for bonding, also known as dative bonding.

Question 16

What does the coordination number indicate?

Answer 16

The number of coordinate bonds formed between the metal ion and its ligands.

Question 17

What is a monodentate ligand?

Answer 17

A ligand that forms one coordinate bond to the central metal ion (one lone pair to donate)

Question 18

What is a bidentate ligand?

Answer 18

A ligand that forms two coordinate bonds to the central metal ion (2 lone pairs to donate)

Question 19

What is a multidentate ligand?

Answer 19

A ligand that forms three or more coordinate bonds to the central metal ion.

Question 20

Give some examples of monodentate ligands (4)

Answer 20

Cl-
H2O
NH3
CN-

Question 21

Name the most common bidentate ligand.

Answer 21

ethane-1,2-diamine

Question 22

Draw ethanedioate; how many coordinate bonds can it form to a transition metal ion?

Answer 22

2 coordinate bonds:

-:O-C=O
/
-:O-C=O

Question 23

Draw benzene-1,2-diol; how many coordinate bonds can it form to a transition metal ion?

Answer 23

(Benzene with 2 OH groups) (Each OH has one lone pair on the O hence 1+1=2)

Question 24

Draw ethane-1,2-diamine. What is its shortened name? How many coordinate bonds does it form?

Answer 24

Coordinate bonds = 2
Shortened name = en

:NH2-CH2-CH2-:NH2

Question 25

What ion is usually formed when a transition metal compound is dissolved in water? What shape is it? Draw an example.

Answer 25

Aqua ion, 6H2O ligands around the central metal ion. Octahedral complex ion is formed.

Question 26

If a transition metal ion has 2 ligands, what shape is it usually?

Answer 26

Linear

Question 27

If a transition metal has 4 ligands, what shape is it usually?

Answer 27

Tetrahedral

Question 28

Name an exception to the general rule that ions with 4 ligands is generally tetrahedral. What shape is it?

Answer 28

Platin --> Square planar --> forms cisplatin

Question 29

What shape is a complex ion if it has 6 ligands?

Answer 29

Octahedral

Question 30

How can complex ions display E-Z or cis-trans isomerism? What shapes of ions does this apply to?

Answer 30

Ligands differ in the way in which they are arranged in space. 2 ligands of the same type can be on the same side of the metal ion (next to each other), which forms E or cis isomer. 2 ligands can also be on opposite sides of the metal ion (not next to each other), which forms the Z or trans isomer. This applies to square planar and octahedral complex ions.

Question 31

What conditions are needed for a complex ion to display optical isomerism?

Answer 31

Usually applies to octahedral molecules with 2 or more bidentate ligands, so that the images are non-superimposable.

Question 32

What is cis-platin used for? Describe its mechanism of action.

Answer 32

Used as anti-cancer drug. It binds to DNA of fast growing cancer cells and prevents cell division, hence reducing the growth of cancer.

Question 33

Which metal ion is present in a haem group?

Answer 33

Fe2+

Question 34

What is the coordination number of a haem group?

Answer 34

6

Question 35

What are the ligands in a haem group?

Answer 35

4 Nitrogen forming the porphyrin ring 1 Oxygen 1 Globin

Question 36

Why is CO toxic?

Answer 36

CO also coordinately bonds to Fe2+, and bonds more strongly to Fe2+ than O2. This stops O2 from bonding to haemoglobin, so O2 cannot be transported around the body.