Transition Metals Flashcards
Where are transition metals located on the periodic table?
d block, outer e- are on the d block
When TM ions form, which orbital is emptied first?
And why?
4s
- 4s and 3d orbitals very close together
-4s and 3d orbitals have been filled, the energy levels swapped over
-due to the addition of electrons in the energies in the orbital
Explain why scandium and zinc aren’t transition metals?
Scandium ion (III) has no electrons in the d orbital
Zinc (II) ion has a full d orbital
Criteria for TM
A transition metal that can form an atom or an ion with an incomplete d orbital
Characteristic Properties of TM, and what causes them?
-form coloured ions/compounds
-catalysts
-variable oxidation states
-forms complexes
-incomplete D-orbital
Describe how colour arises in TM?
-The electrons move from the ground to an excited state
-Visible light is absorbed to promote d electrons to a higher energy level
-Absorbs colour, rest of the colours reflected, forms the complementary colour
Why Li+ and Na+ not used as catalysts?
Only one oxidation state
What is a nucleophile?
electron pair donor
Define coordinate bond
covalent bond in which both electrons are donated by one atom
Define Complex
A molecule with a transition metal ion in the middle with ligands covalently bonded to them
Define Ligand
A ligand is a molecule or ion that forms a co-ordinate bond with a transition metal by donating a pair of electrons.
Define co-ordination number?
Co-ordination number is number of co-ordinate bonds to the central metal atom or ion.
Define Monodentate Ligand
One atom
That can donate a lone pair of electrons to form 1 co-ordinate bond
e.g H2O, NH3 (positively charged)
Cl- , CN- (negatively charged)
Define Bidentate Ligands
Two lone pairs
Each donates a lone pair of electrons to form 2 co-ordinate bonds with the central metal ion
e.g C2O42 (ethanedioate from ethanedioic acid)
H2NCH2CH2NH2
Define Multidentate Ligand
several atoms
Each donating a lone pair of electrons to form several co-ordinate bonds to the central metal ion
e.g EDTA4- (hexadentate specifically)
Why does H2 not act as a ligand?
No lone pairs
What influences the shape of a complex ion?
-size of ligands attached
-coordination number
What is a simple size?
atoms dating lone pair of electrons have similar size
Features of an octahedral complex
-Coordination number of 6
-H2O and NH3 are small ligands so can easily fit around the metal ion
What is an octahedral complex surrounded by water?
hexaaqua ion
Features of a tetrahedral complex?
-Coordination number of 4
-Cl- is a large ligand so only 4 can fit around the central metal ion
Square Planar Complex and Bond Angle
-coordination number of 4
-for Pt2+ and Ni2+
-90*
e.g (NH3)2PtCl2 (cisplatin)
Linear Complex
-Coordination number of 2
-For Ag+
-180*
e.g [Ag(NH3)2]+ (Tollen’s reagent)
Stereoisomers
-Molecules with the same structural formula but different spatial arrangement
Optical Isomers
Non-superimposable mirror images
What type of isomerism do octahedral complexes show?
-cis and trans
-2 identical monodentate ligands are
completely opposite to each other
-180 degrees
How does trans isomerism manifest in octahedral complexes?
2 identical monodentate ligands are completely opposite to each other
180 degrees
What colour precipitate would you see when dilute HNO3 and AgNO3 are added to Cl-?
White ppt of AgCl
How to calculate a redox titration
1- write out 2 half equations
2- combine
3- calculate MOLES of chemical in a burette
4- calculate MOLES of chemical in the flask
5- work out MOLES of ORIGINAL SOLUTION
6- work out the mass/concentration of ORIGINAL SAMPLE, using moles=concentration x vol OR mass=moles x mr
