Transition Elements Flashcards
What is the electron configuration of chromium after 3p6?
4s1 3d5
Define transition element
A d-block element that forms an ion with an incomplete d sub-shell
What properties do transition metals have? Give examples
Variable oxidation states eg Cu2+ and Cu3+ Form coloured ions Eg Fe2+ ions are pale green, Fe3+ ions are yellow Very effective catalysts Eg iron is used in the Haber process for making ammonia Form complex ions Eg [Fe(H2O)6]3+
Reaction of Cu2+ with NaOH
Cu2+(aq) + 2OH-(aq) –> Cu(OH)2(s)
Reaction of Co2+ and NaOH
Co2+(aq) + 2OH-(aq) –> Co(OH)2(s)
Reaction of Fe2+ with NaOH
Fe2+(aq) + 2OH-(aq) –> Fe(OH)2(s)
Reaction of Fe3+ with NaOH
Fe3+(aq) + 3OH-(aq) –> Fe(OH)3(s)
Define ligand
A molecule or ion that can donate a pair of electrons to the transition metal ion to form a coordinate bond
Define complex ion
A transition metal ion bonded to one or more ligand by coordinate bonds
Define coordination number
The total number of coordinate bonds formed between a central metal ion and its ligands
Give the formula and charge of the ligands thiocyanate
:SCN-
Give the formula and charge of a cyanide ligand
:CN-
Give 2 examples of complex ions with an octahedral shape
[Fe(H2O)6]2+
[Cu(H2O)6]2+
What is a bidentate ligand?
A ligand that can donate 2 pairs of electrons to the central metal ion to form 2 coordinate bonds
Eg ‘en’
Define stereoisomerism
Compounds with the same structural formula but with a different arrangement of atoms in space
Which combinations of ligands can form cis-trans isomers?
Square planar: 2 monodentate of the same type, 2 monodentate of another type
Octahedral: 2 monodentate, 2 bidentate
Octahedral: 2 monodentate of one type, 4 monodentate of another type
What combinations of ligands can form optical isomers?
Octahedral: 2 monodentate, 2 bidentate
Octahedral: 3 bidentate
Octahedral: 1 hexadentate
What does the cis isomer of a complex ion look like?
The 2 monodentate ligands of the same type are next to each other
What does the trans isomer of a complex ion look like?
The 2 monodentate ligands of the same type are opposite each other
Optical isomers are…
Non-superimposable mirror images of each other
What complex ion is used as an anti-cancer drug and how does it work?
Cis-platin
It binds to DNA in cancer cells, preventing division
What is the stability constant, Kstab of a complex ion?
The equilibrium constant for the formation of the complex ion in a solvent from its constituent ions
Kstab =
[new complex] / [old complex] x [new ligands]^(moles of new ligands)
A large Kstab value results in…
Formation of a stable complex ion
Complexes with high Kstab values are more likely to form
Colour of Fe^2+(aq) or [Fe(H2O)6]^2+
Green solution
Colour of Fe(OH)2(s)
Green gelatinous precipitate, turning rusty brown on standing
Colour of Fe^3+(aq) or [Fe(H2O)6]^3+
Yellow solution
Colour of Fe(OH)3(s)
Orange gelatinous precipitate
Colour of Cu^2+ or [Cu(H2O)6]^2+
Blue solution
Colour of Cu(OH)2(s)
Pale blue precipitate
Colour of [Cu(NH3)4(H2O)2]^2+
Deep blue solution
Colour of [CuCl4]^2-
Yellow solution
Colour of [Cu(edta)]^2-
Blue solution
Colour of Co^2+(aq) or [Co(H2O)6]^2+
Pink solution
Colour of Co(OH)2(s)
Blue gelatinous precipitate turning beige on standing
Colour of [CoCl4]^2-
Blue solution
Colour of Mn^2+(aq)
Pale pink solution
Colour of MnO4-(aq)
Purple solution
Colour of Cr^3+(aq)
Green solution
Colour of Cr2O7^2-
Orange solution
What is the electron configuration of copper after 3p6?
4s1 3d10
