Transition Metals- (a) Flashcards
Three properties of transition metals
Form coloured compounds
Good catalysts
Form ions of variable oxidation states
Definition of a tranistion metal
Have an incomplete d subshell
Which is filled and emptied first, 3d or 4s
4s
Name and explain 2 instances where 4s and 3d filling patterns deviate
Chromium [Ar] 4s1 3d5. More stable to have 3d5 than 4
Copper [Ar] 4s1 3d10 more stable tp have 3d10 than 3d9
These two also empty 4s1 before 3d
What is a ligand
Molecule or ion that forms a coordinate bond with a transition metal by donating a pair of electrons
What is a coordination number
Number of coordination bonds formed by a transition metal
Compare and contrast the sizes of ligands NH3, H2O and Cl- and the number of bonds they form with metal ions
NH3 and H2O are similar in size and smaller than Cl-.
The size of these ligands mean that normally 6 NH3 or H2O ligands can be placed around a metal ion but only 4 Cl-
Draw the specific shape of 1,2- diaminoethane as a bidentate ligand
see image
Draw the specific shape of Ethane Dioate as a bidentate ligand
see image
Draw the specific shape of EDTA as a multidentate ligand
see image
Draw and name the structure of cis-platin
see image
What happens when a small amount of ammonia is added to hexaaqua copper ions
Ammonia acts as proton acceptor
To form some OH ligands
Light blue ppt forms
What happens when more ammonia is added to hexaquacopper ions that have formed a light blue solution
OH become H2O ligands
previous waters are substituted
Partial substitution of water to ammonia
Deep blue solution formed
Write two equations to represent the adding of ammonia to cause partial substitution of water in hexaaquacopper ions
Cu(h2o)4(OH)2 +4NH3> [Cu(NH3)4(H2O)2]2+ + 2OH- + 2H2O
[Cu(H2O)6]2+ +4NH3> [Cu(NH3)4(H2O)2]2++4H2O
What happens what happens when hexaquacopper ions react with chloride ions
6 waters are substituted for 4Cl- ions
Colour change from blue solution to yellow (or green from mixing) solution
Change in charge from 2+ to 2-
Change in Coordination number from 6 to 4
Write an equation for when hexaquacopper ions react with Cl- ions and a substitution reaction occurs
[Cu(H2O)6]2+ + 4Cl- > [Cu(Cl)4]2- + 6H2O
What happens when hexacobaltaqua ions react with chloride ions
Change in colour from pink to blue (solution)
6 waters are substituted for 4Cl- ions
Change in Coordination number from 6 to 4
Write an equation for the reaction of hexacobaltaqua ions with chloride ions
[Co(H2O)6]2+ +4Cl- > [Co(Cl)4]2- + 6H2O
What is the structure of haemoglobin (and draw picture)
Compare picture to online image
Structure:
Fe with 6 ligands atatched
4 nitrogen groups
one globin group (bonded via N)
Sixth is oxygen when being transported which is lost and substituted by water at the cells
Why does CO poisoning kill you
CO forms strong bonds with Fe and is not readily substituted so oxygen cannot be transported around the body
Which form more stable complexes, multidentate or monodentate ligands
mULTIDENTATE
What is the enthalpy change when in a substitution reaction the coordination number stays the same
negligible
In what type of substitution reaction is enthalpy change higher (give examples)
WHen less bonds are made than broken
i.e. Cl substitutes H2O
What happens to entropy when multidentate ligands replace monodentate ligands (and explain)
Entropy increases
There are now more particles on products side than reactants side
This means the reaction is more likely to occur
Describe the chelate effect
Entropy always increases when multidentate ligands replace monodentate ligands
Using gibbs free energy equation, when delta G is more negative the reaction is more feasible
This explains why multidentate ligands form more stable complexes than monodentate ligands
Colour of [Co(H2O)6]2+
pINK
Colour of [Co(NH3)6]2+
sTRAW
Colour of CoCl4]2-
Blue
