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20 Cards in this Set

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Give a definition of a transition element.
An element where at least it or one of it's ions has a partially filled d sub-shell.
What is the electronic configuration of Cr?
1s2,2s2,2p6,3s2,3p6,4s1,3d5.
Because the electrons like to be as far apart as possible it makes more sense for this configuration than for it to be 4s2,3d4.
What is the electronic configuration of Cu?
1s2,2s2,2p6,3s2,3p6,4s1,3d10.
In copper the 3d shell completely fills before the 4s shell.
What is the order of losing electrons for transition elements?
4s2,3d10
The 4s shell fills first but also loses it's electrons first.
Give a general formula for the reaction of Cu2+, Fe2+, Fe3+, Cr3+, Zn2+ reacting with NaOH.
Xn+ + nOH- -> X(OH)n
Give the equations for Cr3+ and Zn2+ with excess NaOH.
Cr(OH)3 + 3OH- ->Cr(OH)6,3-
Zn(OH)2 +2OH- ->Zn(OH)4,2-
Why are transition metal complexes coloured?
Placing ligands around a central ion causes the energies of the d-orbitals to change. Some of the orbitals gain energy and some lose energy. In an octrahedral complex two go higher ad three go lower. The degree of splitting depends on the central ion and the ligans surrounding it. The energy difference between the levels affects how much energy is absorbed. The amount of energy governs the colour of light absorbed. This colour is then taken out of the light that reaches our eye so the complex would apear the opposite colour so if orange light is absorbed we would see blue.
List the factors that will affect the colour of a transition metal complex.
1) the central ion
2) oxidation state
3)co-ordination number
4) type of ligand
With what type of bonding do ligands bond to transition metal complexes?
Dative covalent bonds
How would you write Chromium (III) with 6 water molecules attached.
[Cr(H2O)6]3+ (the 6 next to the H2O should be sub script)
Describe the colour, bonding and shape of [Cu(H2O)6]2+.
This molecule is a pale blue, it is a Cu 2+ ion bound dative covalently to 6 water molecules. The shape is said to be octrahedral with 4 H2O molecules surrounding the Cu in a cross shape on the same horizontal plane with the other two waters one above the Cu and one below.
Describe the bonding, colour and shape of [Cu(NH3)4(H2O)2]2+
This compound is royal blue and bonds dative covalently in an octrahedral shape.
Describe the bonding, colour and shape of [Cu(NH3)4(H2O)2]2+
This compound is royal blue and bonds dative covalently in an octrahedral shape.
What shape and colour is the [CuCl4]2- complex?
It is tetrahedral and it is yellow.
Give the equations for [Cu(H2O)6]2+ converting to [Cu(H2O)2(NH3)4]2+.
[Cu(H2O)6]2+ + 4NH3 -> [Cu(H2O)4(OH)4]2- + NH4+
This is an acid base reaction, next, woth further addition of ammonia the NH4+ can replace the OH- in ligand exchange to form a royal blue solution.
[Cu(H2O)2(OH)4]2- + NH4+ -> [Cu(H2O)2(NH3)4]2+ + 4OH-
Why are various oxidation states possible in transition elements?
Because the 3d orbitals are so close together in energy it is relatively easy to gain or lose electrons. The most common oxidation state is +2 but for example vanadium can have any number between +2 and +5.
Why are transition elements often good catalysts?
How well a transition element works as a catalyst depends on how many oxidation states in can exhibit and the availability of vacant d orbitals. The reactants can use these vacant orbitals to form temporary bonds that hold them in place while they react.
Give a few examples of transition metals as a catalyst.
V2O2 is used in the contact process 2SO2 + O2 -> 2SO3. and Fe is the catalyst in the Haber process 3H2 + N2 -> 2NH3.
What are some of the biological uses of transition elements?
Manganese is found in bones, tissues and some organs.
Iron is needed to complete haemoglobin.
Cobalt is a cofactor in the insulin hormone system.
Give some economic uses of transition elements.
Iron is used for steel manufacture as well as the Haber process.
Copper is essential for all electrical apparatus .
Nickel is a component of stainless steel.