Transition elements

Question 1

What are transition elements?

Answer 1

d block elements, form at least 1 ion with partially filled d orbital.

Question 2

Why are scandium and zinc not transition elements?

Answer 2

They do not form multiple ions and have full/empty d10 sub shells.

Question 3

What are characteristics of transition elements?

Answer 3

• form compounds where transition elements have different oxidation states
• colour compounds
• act as catalysts

Question 4

What are examples of catalysts being used in industry?

Answer 4

Hetergeneous: Haber process uses iron, Contact process uses V2O5
Homogeneous: hydrogenation of veg fats uses Ni, sulphate formation uses Cu2+

Question 5

What is a ligand?

Answer 5

A molecule or ion that donates a pair of electrons to a central metal ion to form a coordinate bond.

Question 6

What are mono dentate and bidentate ligands?

Answer 6

Mono - can donate 1 pair of electrons eg. water NH3, OH-
Bi - form 2 coordinate bonds eg. 1,2-diaminoethane

Question 7

How are stereoisomers formed?

Answer 7

Some 4 and 6 coordinate complex ions with 2 different mono dentate ligands form cis/trans.
Some 6 coordinate complex ions with mono and bidentate ligands for cis/trans and optical.

Question 8

Why can only octahedral form optical isomers?

Answer 8

With 2 bidentate ligands because otherwise not non-superimposable. Trans not form optical isomers as mirror image = same.

Question 9

How does blood transport oxygen?

Answer 9

With haemoglobin - weak intermolecular forces. Haem group = Fe2+ to form oxyhemoglobin. CO can also bind with stronger bonds, so is irreversible.

Question 10

How can transition elements be used in qualitative analysis?

Answer 10

Fe2 –> Fe3+ used as base for redox titration. Colour change hidden by iodine solid, so looks brown.
Potassium dichromate orange to green.

Test for ammonium ion - when heated with OH-, NH4+ -> NH3 and damp red litmus paper turns blue.