Complex ions and their Colours Flashcards
What is at the centre of a comlex ion?
A transition metal ion.
What is the definition of a complex ion?
A central transition metal ion surrounded by ligands
What is a ligand?
A molecule or ion which donates a pair of electrons to the central metal ion to form a coordinate bond
What is a coordinate bond?
A shared pair of electrons between 2 atoms where both electrons come from the same atom.
What is coordination number?
The total number of bonds formed between the ligand and the central metal ion
Give an example of 3 monodentate ions?
H20, NH3, Cl-
Give an example of two bidentate loigands.
Ethanedioate, C2O4-
The lone bonds are made via the single bonded oxygen’s lone pairs
Ethane-1,2-diamine (ethylenediamine/en)
The Nh2 groups lone pairs make the bonds
Give an example of a multidentate ligand.
EDTA, EDTA4-
It can form 6 coordinate bonds
Ethane-1,2-diamine
It can form 6 coordinate bonds (6 NH2)
What is the shape and bond angle of a complex ion with 6 ligands?
Octahedral, 90 degrees
What ic cisplatin?
Pt(NH3)2Cl2
What is the shape and bond angle of cis platin?
Square planar, bond angle 90 degrees
What type of isomerism do complex ions show?
Cis-trans and optical isomerism
How do you identify cis and trans isomers of complex ions?
Cis - like ligands are 90 degrees apart
Trans - like ligands are 180 degrees apart
What is an optical isomer?
Isomers that are non superimposable images of eachother
What are the 3 ways complex ions can show optical isomerism?
3 bidentate ligands
2 bidentate ligands and 2 monodentate ligands in cis orientation
1 hexadentate ligand, [Cu(EDTA)]2+
What is the use of cisplatin in medicine?
Used as an anti cancer drug. Binds to DNA in cancer cells, preventing cell division. So, the cell dies
It has unwanted side effects (hair loss as it targets quick replicating cells like hair follicles) so trials continue with other platinum based drugs
What is Cu2+ (aq) as a complex ion and its colour?
[Cu(H2O)6]2+ is a blue solution
What is Copper (II) hydroxide as a complex ion and its colour?
Cu(OH)2 = [Cu(OH)2(H2O)4] IS A BLUE PRECIPITATE
What formula, state and colour is the copper (II) ion in with 4 ammonia and 2 water ligands?
[Cu(NH3)4(H2O)2]2+ is a deep blue solution
What state, colour is [CuCl4]2-?
Yellow solution
When reacting Copper (II) with HCL why does it look green?
The reaction between the aqueous copper 2 ions [Cu(H2O)6] ions and the chlorine ions is reversible so both blue and yellow species are present
What is the clour of aqueous Fe2+
Pale green. [Fe(H20)6]2+
What is the colour, state and complex ion of iron II hydroxide, Fe(OH)2?
[Fe(OH)2(H2O)4], Green precipiate
Why does Fe II hydroxide precipitate start to turn brown?
The Fe 2+ ions are being oxidised to Fe 3+ ions, forming iron III hydroxide
What is the equation, state and colour of Fe3+ (aq)?
Yellow solution. [Fe(H2O)6]3+
What state, oxidation number and formula is iron 111 hydroxide, Fe(OH)3?
[Fe(OH)3(H2O)3] orange-brown precipitate
What state, oxidation number and formula is Mn2+ (aq)
Very pale pink
[Mn(H2O)6]2+
What state, oxidation number and formula is manganese 2 hydroxide, Mn(OH)2?
[Mn(OH)2(H2O)4]
Pale brown precipitate. Darkens in air
What state, oxidation number and formula is aqueous Chromium III, Cr3+?
[Cr(H2O)6]3+
Pale purple. Heat to green. Can appear green in solution due to impurities
What state, oxidation number and formula is Chromium 3 hydroxide
Cr(OH)3
[Cr(OH)3(H2O)]
Dark green precipitate
What happens when you add excess OH-, Chromium 3 hydroxide?
[Cr(OH)6]3-
Dark green precipitate dissolves to dark green solution
What state, oxidation number and formula is chromium 3 with 6 ammonia ligands?
[Cr(NH3)6]3+ purple solution
WHt colour is CoCl42-?
From CoCl2.6H2O (s) plus water and excess HCl = BLUE SOLUTION
What colour is CrO42-?
Yellow. From addition of Cr3+ with hot alkaline H202
