Transitions Elements and Qualitative Analysis Flashcards
(51 cards)
Define a transition element
A d-block element that forms at least one stable ion with partially filled d-sub shell
What are the 2 elements in d block that are not considered as transition metals?
Scandium and Zinc
Why are scandium and zinc not considered transition metals?
Scandium only forms Sc3+, where the d orbitals are empty.
Zinc only forms Zn2+ where the d orbitals are full
Which electrons do transition metals lose first when forming ions?
4s
What are some characteristic physical properties of transition metals?
- metallic
- high density
- high melting and boiling point
- shiny
- good conductors of heat and electricity
What are the characteristic chemical properties of transition metals? (4)
- variable oxidation states —> take part in many redox reactions
- coloured compounds/ ions in solution
- good catalysts
- form complex ions
What are the two main ways in which transition metals act as an effective catalyst?
- they provide a surface on which reactions can take place
- they change oxidation states to form intermediates requires for pathways with lower activation energy
Give some examples of transition metal catalysts and the processes/reactions they catalyse? (5)
- iron — Haber process
- vanadium (V) oxide — contact process
- nickel — hydrogenation of alkenes
- manganese (IV) oxide — decomposition of hydrogen peroxide
- copper sulfate — hydrogen production
What is a complex ion?
Transition metal ion bonded to one or more ligands by coordinate bonds.
Define a ligand
Molecule or an ion that can donate a pair of electrons to the metal to form a coordinate bond.
What is a coordinate bond?
A bond in which one of the atom provides both the electrons required for bonding, also known as dative bonding.
What is a monodentate ligand?
A ligand that forms one co-ordinate bond to the central metal ion (one lone pair to donate)
What is a bidentate ligand?
A ligand that forms two coordinate bonds to the central metal ion (2 lone pairs to donate)
What is a multidentate ligand?
A ligand that forms three or more coordinate bonds to the central metal ion.
Give some examples of common monodentate ligands (4).
Cl-, H2O, NH3, CN-
Name the most common bidentate ligand.
ethane-1,2-diamine
How many coordinate bonds does EDTA4- form?
6
EDTA is a chelating agent, what does that mean?
EDTA decreases the concentration of metal ions in the solution by binding to them and forming complex ions.
If a transition metal ion has 2 ligands, what shape is it usually?
linear
If a transition metal ion has 4 ligands, what shape is it usually?
Tetrahedral
Name an exception to the general rule that ions with 4 ligands are tetrahedral. What shape is it?
Platin is square planar —> forms cisplatin
What shape is a complex ion if it has 6 ligands?
Octahedral
How can complex ions display E-Z or cis-trans isomerism? What shapes of ions does this apply to?
Ligands differ in the way in which they are arranged in space. 2 ligands of the same type can be on the same side of the metal ion (next to each other) which forms the E or cis isomer.
2 ligands of the same type can be on opposite sides of the metal ion (not next to each other), which forms Z or trans isomer.
What conditions are needed for a complex ion to display optical isomerism?
Usually applies to octahedral molecules with 2 or more bidentate ligands, so that the mirror images are non-superimposable
