Transition Metals Flashcards
What is the colour of aqueous iron (II)?
Green
What is the colour of aqueous iron (III)?
Yellow
What is the colour of aqueous copper (II)?
Blue
What is the colour of aqueous chromium (III)?
Green
What is the colour of aqueous cobalt (II)?
Pink
What is the colour of the precipitate of iron (II)?
Green
What is the colour of the precipitate of iron (III)?
Brown
What is the colour of the precipitate of copper (II)?
Blue
What is the colour of the precipitate of chromium (III)?
Green
What is the colour of the precipitate of cobalt (II)?
Blue
What is the colour of the solution when iron (II) is added to excess NaOH?
Solution is colourless with a green ppt because it is insoluble in excess NaOH. (could still be faint green sol)
What is the colour of the solution when iron (III) is added to excess NaOH?
Solution is colourless with a brown ppt because it is insoluble in excess with NaOH. (could still be a faint yellow sol)
What is the colour of the solution when copper (II) is added to excess NaOH?
Solution is colourless with a blue ppt because it is insoluble in excess with NaOH. (could still be a faint blue sol)
What is the colour of the solution when chromium (III) is added to excess NaOH?
Deep Green
What is the colour of the solution when cobalt (II) is added to excess NaOH?
Solution is colourless with a blue ppt because it is insoluble in excess with NaOH. (could still be a faint pink sol)
What is the colour of the solution when iron (II) is added to excess ammonia?
Solution is colourless with a green ppt because it is insoluble in excess with NaOH. (could still be a faint green sol)
What is the colour of the solution when iron (III) is added to excess ammonia?
Solution is colourless with a brown ppt because it is insoluble in excess with NaOH. (could still be a faint yellow sol)
What is the colour of the solution when copper (II) is added to excess ammonia?
Deep blue
What is the colour of the solution when chromium (III) is added to excess ammonia?
Violet
What is the colour of the solution when cobalt (II) is added to excess ammonia?
Brown
What is the colour of vanadium (II)?
Purple
What is the colour of vanadium (III)?
Green
What is the colour of vanadate (IV)?
Blue
What is the colour of vanadate (V)?
Yellow
What is the colour of chromium (II)?
Blue
What is the colour of chromium (III)?
Green
What is the colour of chromate (V)?
Yellow
What is the colour of dichromate (VI)?
Orange
What is the colour of tetrachlorocuprate(II)?
Yellow!! (technically green)
What is the colour of tetrachlorocuprate(II)?
Yellow!! (technically green)
What is the colour of tetrachlorocobaltate (II)?
Blue
Define transition metal.
An element/species/atom that forms at least one stable ion that has a partially filled d-subshell
What two period 4, d block metals aren’t transition metals?
Scandium and Zinc
What is the exception to filling the electron orbitals in copper and chromium?
You only put one electron in the 4s orbital before filling the 3d orbital
Explain what is meant by the term “ligand”.
A molecule/species/compound/group which forms a dative covalent bond with a (central) metal ion
What is meant by the term “multidentate” ligands?
A ligand that forms more than one dative covalent bond to the same metal ion per ligand
How does stability vary according to the number of ligands bonded to a metal ion?
Complexes with fewer ligands are more stable because they form with large increases in the entropy of the system.
Describe how transition metals are able to be coloured.
Ligands cause the d-subshell to split into lower and higher energy sections.
Lower energy d-electron can absorb visible light to transition to a higher energy.
The light observed is the light that isn’t absorbed by the metal
What is meant by the term “complex ion”?
A central metal ion that is surrounded in ligands which are molecules that are bonded to the central metal ion via dative covalent bonds.
What affects the colour of an aqueous transition metal of the same species?
Oxidation number
What ligands are attached
Coordinate number (number of dative covalent bonds formed)
What is meant by the term “coordination number” in respect to complex ions?
The number of dative covalent bonds that all the ligands form to one central metal ion.
What is the significance of the molecule “cis-platin” and describe its structure and function.
Cis-platin is a chemical part of a drug used in cancer treatments. It consists of a central platinum ion with 2 chlorine ligands and 2 ammonia ligands where the chlorine ligands are on the same side and the ammonia ligands are on their own side.
Describe how “cis-platin” functions.
It works by diffusing into the individuals cells and the water in the cytoplasm substitutes with the two chlorine ligands such that there are now two ammonia and two water ligands. It is now able to bind to the nitrogen atoms in the bases of the DNA which prevents the DNA from being replicated and therefore the cell cannot divide. This affects cells with a high multiplication rate therefore causing the most damage to tumours.
What conditions are required for the reduction of VO2 +, VO 2+ and V 3+?
Acidified zinc
Write the balanced equilibrium equation that involves the acidification of chromate (VI).
2CrO4 (2-) + 2H (+) -> Cr2o7 (2-) + H2O
Describe the reactants and conditions for the reduction of dichromate (VI) into chromium (III) and chromium (III) into chromium (II).
Zinc and acid
Write the balanced ionic equations for the reduction of dichromate (VI) into chromium (III).
Cr2O7 (2-) + 14H (+) + 3Zn -> 2Cr (3+) + 7H2O + 3Zn (2+)
Write the balanced ionic equations for the reduction of chromium (III) into chromium (II).
2Cr (3+) + Zn -> 2Cr (2+) + Zn (2+)
How would you go about oxidising chromium (III) and what would this produce?
You would add chromium (III) to hydrogen peroxide which acts as an oxidising agent to make chromate(VI)
How could you convert chromium (III) into dichromate(VI)?
Add hydrogen peroxide and to convert into chromate (VI). Then add strong acid to convert the chromate (VI) into dichromate (VI).
What is special about the complex ion [Cr(H2O)3(OH)3]?
It is an amphoteric molecule meaning that it can donate H+ and accept H+.
