Transition metals Flashcards
What is a transition metal?
A d-block element that can form at least one stable ion with a partially filled d-subshell
When is a co-ordinate bond formed and how?
when a transition metal ion reacts with a ligand
- an electron pair on the ligand is donated from the ligand to the central metal ion
How many electrons can a d-subshell hold?
10 electrons
Why are scandium and zinc not transition metals?
They don’t form a stable ion with a partially filled d-subshell
Sc: Sc3+ has an empty d-subshell
Zn: Zn2+ has a full d-subshell
Which 2 elements only have one electron in the 4s orbital?
Cr and Cu
What are the 4 main characteristic properties of transition metals?
Variable oxidation states - The electrons from 4s and 3d sit very close to each other which means electrons are gained and lost using a similar amount of energy.
Formation of coloured ions - Majority are coloured
Catalytic activity
Complex ion formation
What is a complex ion?
Where a central transition metal ion is surrounded by ligands bonded by co-ordinate bonds
What is a ligand?
An atom, ion or molecule that has at least one lone pair of electrons.
Outline the 3 types of ligands and give examples of them
Monodentate - only have one lone pair of electrons available to form one co-ordinate bond e.g: H2O, NH3 and Cl-
Bidentate - only have two lone pair of electrons available to form two co-ordinate bonds e.g: ethanedioate ion C2O4 2- & ethane-1,2-diamine H2NCH2CH2NH2
Multidentate - have more than 1 coordinate bond e.g: EDTA4-
What is the coordination number?
The number of coordinate bonds in a complex - not the number of ligands
Which ligands can form 6 coordinate bonds around the central ion?
H2O and NH3
Which ligands can form 4 coordinate bonds around the central ion?
Cl-
Which ligands can form 3 coordinate bonds around the central ion?
EDTA4-, ethanedioate
State the bond angle and coordination number for octahedral shapes
6, 90°
State the bond angle and coordination number for tetrahedral shapes and the example you need to know
4, 109.5°, [CuCl4]2-
State the bond angle and coordination number for square planar shapes and the example you need to know
4, 90°, cis-platin Pt[(NH3)2(Cl)2]
State the bond angle and coordination number for linear shapes and the example you need to know
2, 180°, Tollens’ reagent [Ag(NH3)2]+
How do you calculate the oxidation state for the transition metal in the complex?
Total oxidation state of complex - total oxidation state of ligands
What is haem?
The multidentate ligand found in haemoglobin
What type of transition metal ion complexes form cis-trans?
- Octahedral complexes with 4 ligands of the same type and 2 ligands of a different type (must all be monodentate)
- Square planar complexes with 2 ligands of the same type and 2 ligands of a different type
What type of transition metal ion complexes form optical isomerism?
Octahedral complexes with 3 bidentate ligands
What happens to the orbitals when we attach ligands?
The d-orbital gains energy and splits and we end up with 2 energy levels, 3 at the bottom and 2 at the top. The energy gap between is delta E.
What must happen in order for electrons to jump orbitals?
Energy from light must equal delta E
What is the size of delta E dependent on?
- The central metal ion and its oxidation state
- Type of ligand
- Coordination number
What is the formula to calculate the energy absorbed by the electrons?
Delta E = hv = hc/y
is the metal/ligand lewis acid/base
metal = e- acceptor = lewis acid
ligand = e- donor = lewis base
