Transition Elements Active Recall Questions

Question 1

State what is meant by a bidentate ligand

Answer 1

A ligand that donates two electron pairs and forms two co-ordinate bonds to a metal ion

Question 2

What does co-ordination number mean?

Answer 2

the number of co-ordinate bonds

e.g. [Mn(H2O)6]2+ forms 6 co-ordinate bonds due to the Mn2+ ion forming 6 co-ordinate bonds to each NH3

Question 3

Cu2+ + excess NaOH?

Answer 3

Cu2+ + 2OH- -> Cu(OH)2

forms blue precipitate

Question 4

Cu2+ + excess NH3?

Answer 4

[Cu(H2O)6]2+ + 4NH3 -> [Cu(H2O)2(NH3)4]2+ + 4H2O

forms a deep blue solution

Question 5

Cu2+ + HCl?

Answer 5

[Cu(H2O)6]2+ + 4Cl- -> [Cu(Cl)4]2- + 6H2O

forms a yellow solution

Question 6

Co2+ + excess NaOH?

Answer 6

Co2+ + 2OH- -> Co(OH)2

forms blue precipitate

Question 7

Co2+ + excess NH3?

Answer 7

[Cu(H2O)6]2+ + 6NH3 -> [Cu(NH3)6]2+ + 6H2O

Question 8

Co2+ + HCl?

Answer 8

[Co(H2O)6]2+ + 4Cl– → [CoCl4]2– + 6H2O

Question 9

What is the definition of a transition element, and why is zinc or scandium not a trasition elements?

Answer 9

A transition element is an element that can form an ion with a partially filled d-subshell

• Sc3+ - 1s22s22p63s23p6 (no electrons in d subshell)
• Zn2+ - 1s22s22p63s23p63d10 (full d sub-shell)

Question 10

Explain how a molecule with two NH2 groups at the ends of the carbon chain can act as a bidentate ligand

Answer 10

capable of donating two electron pairs to the metal ion to form two co-ordinate bonds due to having two lone pairs, one on each NH2 group.