Transition elements

Question 1

d-block element

Answer 1

An element with its highest energy e- in the d-subshell

Question 2

transition metal

Answer 2

A d-block element which forms at least one ion with an incomplete d-subshell

Question 3

What three types of reactions can transition elements undergo?

Answer 3

• ligand exchange
• precipitate
• redox

Question 4

chemical properties of transition elements (4)

Answer 4

• colourful
• good catalysts
• variable oxidation states
• complex ions with variety of ligands

Question 5

physical properties of transition elements (5)

Answer 5

• ductile
• malleable
• high melting/boiling pt
• hard/dense
• sonorous

Question 6

Why are transition elements good catalysts?

Answer 6

• variable oxidation states
• provide a surface which can absorb reactants (form complex ions)

Question 7

two examples of reactions which use transition metals as catalysts

Answer 7

• Ni (alkene –> alkane)
• V2O5 Contact process (SO2 + O2 –> 2SO3)

Question 8

ligand

Answer 8

A molecule or ion that can donate a pair of e- to the transition metal ion

Question 9

complex ion

Answer 9

A transition metal bonded to ligands by coordinate bonds

Question 10

coordinate number

Answer 10

Total number of coordinate bonds between a central metal ion and ligands

Question 11

shape of complex ion with 4 coordinate bonds

Answer 11

square planar (90°)

Question 12

shape of complex ion with 6 coordinate bonds

Answer 12

octahedral (90°)

Question 13

bidentate ligands

Answer 13

ligands with two lone pairs of e-:
- en
- ethanedioate (2-)

Question 14

hexadentate ligands

Answer 14

ligands with six lone pairs of e-:
- edta (4-)

Question 15

neutral ligands (monodentate)

Answer 15

• H2O
• NH3

Question 16

charged ligands

Answer 16

• Cl-
• OH-
• CN-
• SCN-

Question 17

which two transition metals have unusual e- configurations?

Answer 17

Cr and Cu

Question 18

which d-block elements are not transition elements?

Answer 18

• Zn (Zn2+ has a full d-subshell)
• SC (Sc3+ doesn’t have a d-subshell)

Question 19

Cu2+ with NaOH(aq)

Answer 19

blue solution –> blue ppt
Cu(OH)2(s)

ppt insoluble in excess

Question 20

Fe2+ with NaOH(aq)

Answer 20

pale green solution –> dark green ppt (goes brown on standing in air)
Fe(OH)2(s)

ppt insoluble in excess

Question 21

Fe3+ with NaOH(aq)

Answer 21

pale yellow solution –> orange brown ppt

Fe(OH)3(aq)

ppt insoluble in excess

Question 22

Mn2+ with NaOH(aq)

Answer 22

pale pink solution –> light brown ppt (darkens on standing in air)

Mn(OH)2(s)

ppt insoluble in excess

Question 23

Cr3+ with NaOH(aq)

Answer 23

violet solution –> grey green ppt

Cr(OH)3(s)

ppt dissolves in excess to form a dark green solution

[Cr(OH)6]3-(aq)

Question 24

which ions react the same way with NH3(aq) as they do with NaOH(aq)

Answer 24

Fe2+
Fe3+
Mn2+

Question 25

Cu2+ with NH3(aq)

Answer 25

blue solution --> blue ppt Cu(OH)2(s) ppt dissolves in excess to form a dark blue solution (ligand exchange) [Cu(NH3)4(H2O)2]2+(aq)

Question 26

Cr3+ with NH3(aq)

Answer 26

violet solution --> grey green ppt Cr(OH)3(s) ppt dissolves in excess to form a purple solution (ligand exchange) [Cr(NH3)6]3+(aq)