Transition Elements Flashcards
Transition element
A d block element that can form at least one stable ion with an incomplete d sub-shell.
Which elements are not transition elements in the d block?
Scandium and Zinc- because they don’t form a stable ion with a partially filled d sub shell.
Which transition elements have a 4s1 sub shell (different from the rest) and why?
Cr and Cu because having a 3d5 and 3d10 sub-shell give additional stability to atoms.
Why is scandium not a transition elements?
It only form one stable ion of Sc 3+ which has an empty 3d subshell (not partially filled)
Which orbital do you remove first?
You remove from the 4s SUB LEVEL FIRST!!!!!!
Why zinc not a transition element?
It only form 1 stable ion of Zn2+ which has a full d subshell (not partially filled)
What are the three main properties of transition metal?
- Variable oxidation states
- Form coloured ions
- Good catalysts
Why do transition metals have variable oxidation states?
Because 4s and 3d sub levels are so close
What are some processes where a transition metal is used as a catalyst
- Haber process (Iron)
- Hydrogenation of alkenes
(Heterogenous catalyst)
What formula do metal ions have dissolved in water?
[M(H2O)6]^n+
Ligand
Molecule or ion that donates a pair of electrons to a central metal ion to form a dative covalent bond.
Coordination number
Number of dative coordinate bonds attached to the central atom
Monodentate ligands + examples
Donates one lone pair and forms one coordinate bond to a metal ion.
H2O:
:NH3
:CN-
:Cl-
Bidentate ligands + examples
Donates 2 lone pairs and forms two coordinate bonds to a metal ion.
- Ethanedioate
- Ethane-1,2- diamine
Ligands with more than two coordinate bonds
Multidentate ligands
Examples of small ligands
H2O:, :NH3, :CN- —> can fit 6 around a central metal (octahedral)
Examples of larger ligands
:Cl- (fits 4 bonds) and 1,2- diaminoethane + ethanedioate ion (normally forms 3)
Example of square planar complex
Pt[(NH3)2Cl2)aq (cis platin)
Total oxidation state of metal equation
Total oxidation state - total oxidation state of ligands
Optical isomerism in complex ions
Octahedral complexes with 3 bidentate ligands form non-superimposable images.
What type of stereoisomerism do complexes show?
- Cis-trans isomerism
- Octahedral complexes
Cis-trans isomerism
- Octahedral complexes with 4 ligands of the same type and 2 ligands of a different type display cis- grands isomerism.
180= opposite = trans
<180= adjacent = cis
-Square planar complexes with 2 ligands of the same type and 2 ligands of different type display cis-trans isomerism
How do ligand substitution reaction allow haemoglobin to transport oxygen in blood?
Oxygen bonds to Fe2+ and when required O2 is released (equilibrium)
What makes a molecule a square planar
- Complex has no more than two identical ligands attached to the central metal ions
- 90” bond angle
Describe the action of one of platin stereoisomers in cancer treatment
The cis isomers binds the cancer cell’s DNA and stops it from replicating
