Module 5: Chaper 24 - Transition Metals/ Elements.

Question 1

What is the DEFINITION of a Transition Metal?

Answer 1

A d-block element which forms at least 1 ion with an incomplete d-orbital/ sub-shell.

Question 2

Which 2 elements in the first row of the d-block have unusual electron configurations?

Answer 2

• Chromium (4s¹ 3d⁵).
• Copper (4s¹ 3d¹⁰).

Question 3

Which 2 elements in the first row of the d-block are NOT transition elements?

Answer 3

Scandium (Sc) and Zinc (Zn) because they are not able to form at least 1 ion with an incomplete d-orbital/ sub-shell.

Question 4

Why is the d-block called the “d-block”?

Answer 4

Because the highest energy electrons are in the d orbitals/sub-shell.

Question 5

Give 3 chemical properties of transition elements and their compounds.

Answer 5

• They can form multiple oxidation states.
• They can form coloured compounds.
• They can act as catalysts.

Question 6

Give 3 physical properties of transition elements.

Answer 6

• High Melting and Boiling Points.
• They are malleable (can be shaped).
• They are good conductors of heat and electricity.

Question 7

What is the DEFINITION of a ligand.

Answer 7

A ligand is a species (molecule or ion) that can donate a pair of electrons to a central metal ion to form a coordinate/dative covalent bond.

Question 8

What is the DEFINITION of a coordination number.

Answer 8

The amount of coordinate bonds which a metal ion forms in a complex ion.

Question 9

What is the DEFINITION of a dative/ coodinate bond.

Answer 9

A covalent bond which has been formed where one of the bonded atoms has donated both electrons in its shared pair to a central metal ion in a complex ion.

Question 10

What is the DEFINITION of a ligand substitution reaction.

Answer 10

A reaction where one ligand in a complex ion is substituted by another ligand.

Question 11

What is the DEFINITION of a complex ion?

Answer 11

A transition metal ion bonded to one or more ligands by coordinate (dative covalent) bonds.

Question 12

Give some examples of a neutral ligand.

Answer 12

• Ammonia :NH₃
• Water H₂0:

Question 13

Give some examples of a charged ligand.

Answer 13

• Hydroxide :OH^-
• Cyanide :CN^-
• Chloride :Cl^-

Question 14

Explain what a MONODENTATE ligand is and give an example.

Answer 14

• A ligand which forms 1 coordinate (dative covalent) bond to a central metal ion in a complex ion.
• NH₃, H₂O, OH^-, CN^-, Cl^-.

Question 15

Explain what a BIDENTATE ligand is and give an example.

Answer 15

• A ligand which forms 2 coordinate (dative covalent) bonds to a central metal ion in a complex ion.
• (en) NH₂CH₂CH₂NH₂.

Question 16

Explain what a HEXADENTATE ligand is and give an example.

Answer 16

• A ligand which forms 6 coordinate (dative covalent) bonds to a central metal ion in a complex ion.
• (edta^4-).

Question 17

What is the colour of Cu²⁺_(aq)?

Answer 17

Blue Solution.

Question 18

What colour is the precipitate formed by adding NaOH dropwise to Cu²⁺_(aq)? What is the ionic equation for the formation of this?

Answer 18

• Blue Precipitate.
• Cu²⁺_(aq) + 2OH^-_(aq) → Cu(OH)_2(s).

Question 19

What is the colour of Fe²⁺_(aq)?

Answer 19

Pale Green Solution.

Question 20

What colour is the precipitate formed by adding NaOH dropwise to Fe²⁺_(aq)? What is the ionic equation for the formation of this?

Answer 20

• Dark Green Precipitate which goes brown standing in air.
• Fe²⁺_(aq) + 2OH^- → Fe(OH)_2(s).

Question 21

What is the colour of Fe³⁺_(aq)?

Answer 21

Pale Yellow Solution.

Question 22

What colour is the precipitate formed by adding NaOH dropwise to Fe³⁺_(aq)? What is the ionic equation for the formation of this?

Answer 22

• Orange-brown Precipitate.
• Fe³⁺_(aq) + OH^-_(aq) → Fe(OH)_3(s).

Question 23

What is the colour of Mn²⁺_(aq)?

Answer 23

Pale Pink Solution.

Question 24

What colour is the precipitate formed by adding NaOH dropwise to Mn²⁺_(aq)? What is the ionic equation for the formation of this?

Answer 24

• Light brown Precipitate which darkens on standing in air.
• Mn²⁺_(aq) + OH^-_(aq) → Mn(OH)_2(s).

Question 25

What is the **colour** of **Cr³⁺_(aq)**?

Answer 25

Violet Solution.

Question 26

What **colour** is the **precipitate** formed by adding **NaOH** *dropwise* to **Cr³⁺_(aq)**? What is the ionic equation for the formation of this?

Answer 26

- Grey-green precipitate. - Cr³⁺_(aq) + OH^-_(aq) → Cr(OH)_3(s).

Question 27

What **colour** is the **precipitate** formed by adding **NaOH** *in excess* to **Cr³⁺_(aq)**? What is the complex ion which is formed?

Answer 27

- The precipitate dissolves and a Dark Green Solution is formed. - [Cr(OH)₆]^3-_(aq).

Question 28

What **colour** is the **precipitate** formed by adding **NH₃** *dropwise* to **Cu²⁺_(aq)**? What is the ionic equation for the formation of this?

Answer 28

- Blue Precipitate. - Cu²⁺_(aq) + 2OH^-_(aq) → Cu(OH)_2(s).

Question 29

What **colour** is the **solution** formed by adding **NH₃** *in excess* to **Cu²⁺_(aq)**? What is the equation for the formation of this?

Answer 29

- The precipitate dissolves and a Dark Blue Solution is formed (**LIGAND EXCHANGE**). - [Cu(H₂O)₆]²⁺_(aq) + 4NH_3(aq) —> [Cu(NH₃)₄(H₂O)₂]²⁺_(aq) + 4H₂O_(l).

Question 30

What **colour** is the **precipitate** formed by adding **NH₃** *dropwise* to **Cr³⁺_(aq)**? What is the ionic equation for the formation of this?

Answer 30

- Grey-green precipitate. - Cr³⁺_(aq) + 3OH^-_(aq) → Cr(OH)_3(s).

Question 31

What **colour** is the **solution** formed by adding **NH₃** *in excess* to **Cr³⁺_(aq)**? What is the equation for the formation of this?

Answer 31

- The precipitate dissolves and a Purple Solution is formed (**LIGAND EXCHANGE**). - [Cr(H₂O)₆]³⁺_(aq) + 6NH_3(aq) —> [Cr(NH₃)₆]³⁺_(aq) + 6H₂O_(l).

Question 32

What colour change do you see when Cl^-_(aq) ions are added to Cu²⁺_(aq)? What is the equation of the reaction that takes place?

Answer 32

- Blue Solution to Yellow Solution. - [Cu(H₂O)₆]²⁺ + 4Cl^- ⇌ [CuCl₄]^2- + 6H₂O.

Question 33

What **two** shapes and bond angles could a 4-coordinate complex have?

Answer 33

* Tetrahedral (109.5°). * Square Planar (90°).

Question 34

When filling or removing electrons in an atom, is 4s or 3d filled/ removed first?

Answer 34

4s.

Question 35

What shape and bond angle does a 2-coordinate complex have?

Answer 35

Linear (180°).

Question 36

What shape and bond angle does a 6-coordinate complex have?

Answer 36

Octahedral (90°).

Question 37

Identify 1 transition metal used as a heterogeneous catalyst.

Answer 37

Iron (Fe) in the Haber Process or Nickel (Ni) in the hydrogenation of alkenes.

Question 38

What is cis-platin and how does it work? Give it's formula.

Answer 38

* Cis-platin is a chemotherapy drug which binds to the DNA of cancer cells preventing cancer cell division. * [Pt(NH₃)₂(Cl)₂].

Question 39

What type of isomerism can you get with octahedral complexes with 2 or more bidentate ligands?

Answer 39

Optical Isomerism.

Question 40

Explain what happens to Haemoglobin in the lungs and close to respiring cells.

Answer 40

* Lungs: Oxygen (O₂) binds to Haemoglobin to make Oxyhaemoglobin when oxygens concentration is high. * Respiring Cells: O₂ ligand of Oxyhaemoglobin is substituted by CO₂ to make Carboxyhaemoglobin.