Transition Metals Flashcards
(49 cards)
What is a ligand
An atom, ion or molecule which can donate a lone pair of electron.
Define coordinate bonding
It is when the shared pair of electrons in the covalent bond come from only one of the bonding atoms
What is coordination number
The number of coordinate bonds formed to a central metal ion
Give examples of monodentate, bidentate and multidentate ligand
Monodentate : Cl-, H2O, NH3
Bidentate : NH2CH2CH2NH2 and C2O4^2- (ethanedioate ion)
Multidentate : EDTA^4- can form 6bonds
Give equation of incomplete substitution reaction between copper and ammonia, then state the colour change
[Cu(h2o)6]^2+ + 4NH3 -> [Cu(Nh3)4(h2o)2]^2+ + 4H2o
From pale blue to deep blue solution
Why would there be a change in coordination number when Cl ligand is involved
Cl- is a larger ligand than the uncharged h2o and nh3
When [Cu(h2o)6]^2+ is reacted with Cl ligand, what forms and state the colour change
[CuCl4]^2-
Yellow/green solution
If solid copper chloride (or any other metal) is dissolved in water, what does it form?
Aqueous [Cu(h2o)6]^2+ complex forms
NOT the CuCl4 complex!!!
Colour of [CoCl4]^2-
Blue solution
When would partial substitution of ethanedioate ions occur
When dilute aq solution containing c2o4^2- ions are added to a solution containing aq Cu2+
4 h2o will be replaced
Give an example of an iron(ii) complex with a multidentate ligand
Ahem
How does Fe(ii) in haemoglobin work in the body
In the body both H2O and O2 bind to Fe2+ ions as ligands, so the complex can transport O2 two where it’s needed then swap to h2o molecule.
In lungs where O2 concentration is high, water ligands are substituted for O2 molecules to form oxyhaemoglobin which is carried around body in blood
How can CO harm human in terms of haemo
What are the impacts on the human
CO is toxic to humans as it can form a strong coordinate bond with haemoglobin.
This is a stronger bond than that made with oxygen and so it replaces the oxygen attaching to the haemoglobin
impact - cause dizziness, headaches, even death
Chemical properties of transition metals, name 4 and what is it caused by
Form complex ions
Various oxidation states
Form coloured compounds
Good catalysts
These are caused by presence of an incomplete d sub shell
Physical properties of transition metals and question why
High density
Good electricity conductor
High melting and boiling point
- due to metallic bonds formed, electrostatic force of attraction between positive ions and sea of delocalised electrons
In period 4, which 2 are not transition metals, and why
Sc and Zn
Sc is 3d1 4s2, it must form Sc3+ ions so there would be no electrons in the d she’ll.
Zn is 3d10 4s2, when it forms Zn2+, there would be a full d she’ll
Why is electronic configuration of
Cr: [Ar] 3d54s1 and
Cu: [Ar] 3d10 4s1
For Cr, it prefers one electron in all 3d sub shell, making it more stable
For Cu, it prefers a full 3d sub shell, making it more stable as well
What is the chelate effect
The substitution of monodentate ligand with a bidentate or multidentate ligand leads to a more stable complex
Redox potentials tell you how easily it is reduced to a lower oxidation state. The more positive it is the more/less stable is it and the more or less likely will it be reduced
The more positive, the less stable, and the more likely it will be reduced
What 2 factors affect redox potentials in transition metal chemistry
Ph
Ligands (depends on how well they bind to the metal ion)
Formation of coloured ions is associated with incomplete d orbital, what are the 3 things that cause colour changes to arise from?
Changes in
Oxidation state
Ligand
Coordination number
Colour of [Co(NH3)6]2+
Yellow
Colour of [Co(NH3)6]3+
Brown
Colour of change of Co(H2o)6^2+ + 4Cl- -> [CoCl4]2-
Pink to blue
