Developing metals (DM) Flashcards
Transition metal definition
D-block elements which form one or more stable ions which have incompletely filled d-orbitals
In the first row of d-block elements, which elements are not transition metals?
Sc and Zn
Sc only forms 1 ion, which has an empty d subshell
Zn only forms 1 ion, which has a full d-subshell
Electronic configuration of d-block elements:
- 4s fills before 3d as 4s has a lower energy
- Cr and Cu are exceptions- an electron in the 4s orbital moves into the 3d as this gives a lower energy
- Electrons then fill 3d subshells singly before pairing up
- When ions are formed, the 4s orbital always loses its electrons first
Determining the iron content using a redox titration:
- Fe (II) ions can be oxidised to Fe (III) ions by potassium manganate (VII) in acidic solution
- Known volume of Fe (II) solution is titrated with potassium manganate (VII) solution of known concentration
- Potassium manganate in burette
- End point is when the first permanent pink colour is observed
Common oxidation states of iron
Fe (II)
Fe (III)
Common oxidation sates of copper
Cu (I) - unstable
Cu (II)
Colour of iron (II) hydroxide
Colour of Iron (III) hydroxide
Dark green
Red/orange
Colour of aqueous iron (II) ions
Colour of aqueous iron (III) ions
Pale green
Yellow
Colour of aqueous copper (I) ions
Colour of aqueous copper (II) ions
Unstable - no colour
Pale blue
Colour of copper (II) hydroxide
Colour of copper (II) ammonia complex
Blue
Dark blue
Describe what happens when ammonia solution is added to copper (II) hydroxide
- Ammonia = source of OH- ions
- Pale blue precipitate of copper (II) hydroxide dissolves to give a deep blue solution of a copper ammonia complex ion
PALE BLUE——————DARK BLUE
Ligand definition
A negatively charged ion or neutral molecule with a LONE PAIR of electrons which it donates to a central TRANSITION METAL ION to form a COORDINATE bond
Complex ion definition
A transition metal ion or atom surrounded by a number of ligands
Ligand substitution definition
+ when it occurs
When a ligand is swapped for another ligand
Usually results in a colour change
Occurs if the new complex formed is more stable than the previous complex
Sometimes substitution is only partial
Writing complex ions
The overall charge of the complex ion is the sum of the charge on the central metal ion + the charges on the ligands
(Fe(H2O)6)^2+
(Fe(H2O)6)^3+
(Cu(H2O)6)^2+
(Cu(NH3)4)^2+
(CuCl4)2-
Another word to describe a coordinate bond:
Dative
Monodentate ligand definition
a ligand that attaches to a transition metal through one atom only (eg OH-, H2O)
Bidentate ligand definition
a ligand with 2 atoms with lone pairs or negative charges, which forms 2 bonds to a metal ion
Structure of ethanedioate
How does it act as a ligand?
-^OO=C-C=OO^- (see notes)
Bidentate ligand- has 2 atoms with lone pairs which forms 2 coordinate bonds to a metal ion
Iron (II) hydroxide and iron (III) hydroxide reaction/colour change with ammonia solution
Both do not form complexes with ammonia
Coordination number definition:
the number of coordinate bonds that are formed with the central metal atom
Usual coordination numbers are 4 and 6
Shape of complex ion and bond angle when coordination number is 6:
Octahedral
90 degrees