6.2.1 General Properties of Transition Metals

Question 1

What’s special about the configurations of Cr and Cu

Answer 1

Cr is [Ar] 3d5 4s1 not [Ar] 3d4 4s2

Cu is [Ar] 3d10 4s1 not [Ar] 3d9 4s2

(more stable) (all transition metals lose their 4s outer electrons first, and gain them too)

Question 2

General properties of transition metals (different from usual metals)

Answer 2

• Variable oxidation states
• Form complex ions
• Form coloured compounds
• Act as catalysts

Question 3

What is meant by variable oxidation states?

Answer 3

• Transition metals can form more than 1 positive ion
• Roman numerals indicate the charge of the ion

Question 4

What are complex ions in reference to properties of transition metals

Answer 4

• Central transition metal ion
• Surrounded by molecules called ligands
• Can form a variety of ligands
• Eg. Cr 3+
• [Cr(NH3)6]3+, [Cr(OH)6]3- and [Cr(H2O)6]3+ complex ions

Question 5

How can transition metals act as catalysts?

Answer 5

• They have variable oxidation states
• During catalysis transition metal changes to various oxidation states
• By accepting or donating electrons
• Substances can be adsorbed onto their surface and be activated

Question 6

What is a complex ion?

Answer 6

• Central transition metal ion
• Surrounding ligands form coordinate bonds with transition metal ion (2 lone pairs of electrons donated from each ligand to the central ion)

Question 7

What is a ligand

Answer 7

• A molecule or ion donating a lone pair of electrons
• To a transition metal
• By dative covalent bonding
• Same as nucleophile

Question 8

What is the coordination number?

Answer 8

• Total number of coordinate bonds to central transition metal

Question 9

Examples of ligands

Answer 9

Question 10

What are monodentate ligands? Examples?

Answer 10

• Form 1 coordinate bond to central metal ion
• H2O
• NH3
• Cl-
• CN-

Question 11

What are bidentate ligands? Examples?

Answer 11

• Ligands that form 2 coordinate bonds to the central metal ion
• Each ligand contains 2 atoms with lone pairs of electrons
• 1,2-diaminoethane (H2NCH2CH2NH2)
• Ethanedioate ion (C2O42- )

Question 12

What are multidentate ligands?

Answer 12

• Ligands that form 2 or more coordinate bonds to the central transition metal ion
• Contain more than 2 atoms with lone pairs
• EDTA4-

Question 13

Examples of neutral ligands?

Answer 13

• Water and ammonia

Question 14

Water and ammonia ligands :

Answer 14

• Small ligands
• Form 6 dative bonds with central transition metal ion
• 6 ligands form 6 bonds
• Coordination number is 6

Question 15

Hydroxide and chloride ion ligands :

Answer 15

• Negatively charged ligands
• OH- ligand is small, 6 dative bonds
• Cl- ligands large, so only 4 dative bonds