Lecture 1

Question 1

Define transition elements

Answer 1

transition elements have partly
filled d- or f- subshells

Question 2

where are the transition elements found

Answer 2

• Groups 3 to 11, lying between the s-block
  elements and the p-block elements
• f-block elements (lanthanides,
  actinides)

Question 3

What is the Aufbau principle?

Answer 3

4s subshell is lower in energy than 3d subshell so 4s is filled before 3d
e.g. 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p

Question 4

Whats different about the electron configuration of Cu and Cr atoms?

Answer 4

Cr = 3d5 4s1
Cu = 3d10 4s1
This avoids pairing energy as 4s1 electrons are unpaired

Question 5

Which metals in the d block arent TM?

Answer 5

• Transition metal cations have no 4s
  electrons!
• Cu has d10 configuration. However, since it
  forms ions with partly-filled d-subshells we
  include it as TM
• Zn and Zn2+ have d10 configuration and
  are not considered TMs

Question 6

Why does the 3rd ionisation energy of elements after Mn not follow the trend?

Answer 6

• 3rd IE of Fe, Co, Ni, Cu, Zn are much lower than expected- don’t follow the previous trend
• as before Fe electrons are removed from a singly occupied orbital whereas from Fe onwards they are removed from doubly-occupied orbitals
• pairing energy makes it easier to remove the electrons so IE is less

Question 7

Give the periodic trend in IE

Answer 7

slow increase as the effective nuclear charge (zeff) of the metal increases

Question 8

Describe why there is discontinuity in IE across the period

Answer 8

drop at the d6-d5 transition (third IE for Fe and second for Mn) repulsion between two electrons in the same d-orbital makes it easier to remove the sixth electron

Question 9

Which elements can achieve group oxidation state?

Answer 9

Group oxidation state (loss of all valence
electrons): can be achieved by elements that lie towards the left of the d-block but, not by elements on the right

Question 10

Give the equation for Fe3+ catalysed decomp of H2O2

Answer 10

H2O2 + 2Fe3+ = O2 + 2Fe2+ + 2H+
H2O2 + 2Fe2+ + 2H+ = 2H2O + 2Fe3+

Question 11

What type of reaction is Fe3+ catalysed decomp of H2O2? (elephants toothpaste exp)

Answer 11

decomposition and catalysis

Question 12

Describe the abundances and location of commonly found TM

Answer 12

• Concentration of Fe in the Earth’s crust: far greater than those of the other transition metals summed together
• Element distribution in sea water: more even
• Human body: concentrations generally higher than in ocean water (many TMs are biologically necessary)

Question 13

Give some applications of TM

Answer 13

• Structural materials; Fe alloyed with e.g. Cr, V, Mo, Ni, Ti
• Electrical conductors; Cu
• Batteries; MnO2, Ni, Zn
• Magnetic materials; Fe + Co, Ni, у-FeO3 or CrO2, Nd2Fe14B (neodymium magnets)
• Catalysts; Co, Cu
• Pharmaceuticals; Fe, Co, Zn, cisplatin (anti-cancer agent)
• Pigments; CoAl2O4 (blue), CdS (yellow), TiO2 (white)