5.3.1 Transition Elements Flashcards
Define a transition element
A d block element that forms at least one stable ion with partially filled d subshell
Where are the transition metals located in the periodic table?
In the middle block from Ti to Cu
What are the 2 elements in d block that are not considered as transition metals?
Scandium and zinc
Why is scandium and zinc not considered as transition metals?
Scandium only forms Sc³⁺, where the d orbitals are empty
Zinc only forms Zn²⁺ where the d orbitals are full
What is the noble gas configuration of chromium?
[Ar] 4s¹ 3d⁵
What is the noble gas configuration of copper?
[Ar] 4s¹ 3d¹⁰
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 conductor of heat and electricity
What are the characteristic chemical properties of transition metals?
- Variable oxidation states
- Coloured compounds/ions in solution
- Good catalysts
- Form complex ions
In potassium manganate (VII), what is the oxidation number of Mn?
Mn = +7
What are the 2 main ways in which transition metals act as an effective catalyst?
- They provide a surface on which reaction can take place
- They change oxidation states to form intermediates required for pathways with lower activation energy
Give some examples of transition metal catalysts and the processes/reactions they catalyse?
- 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 metals 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 does the coordination number indicate?
The number of coordination bonds formed between the metal ion and its ligands
What is a mono/unidentate 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 co-ordinate bonds to the central metal ion
(2 lone pairs to donate)
What is a multidentate ligand?
A ligand that forms three or more co-ordinate bonds to the central metal ion
Give some examples of common monodentate ligands
Cl⁻, H₂O, NH₃, CN⁻
Name the most common bidentate ligand
ethane- 1.2- diamine
en
How many coordinate bonds does EDTA⁴⁻ form?
six
What ion is usually formed when a transition metal compound is dissolved in water? What shape is it?
Aqua ion, 6 H₂O ligands around the central metal ion.
Octahedral complex ion is formed
If a. transition metal ion has 2 ligands, what shape is it usually?
Linear
If a transition metal has 4 ligands, what shape is it usually?
Tetrahedral
Name an exception to the general. rule that ions with 4 ligands is generally. 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 EZ 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 eachother), 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 eachother), which forms the Z or trans isomer. Applies to square planar and octahedral complex ions
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
What is cis-platin used for? Describe its mechanism of action
It is used as an anti cancer drug
It binds to DNA of fast growing cancer cells and prevents cell division, hence reducing the growth of cancer
Which metal ion is present in haem group?
Fe²⁺
What is the coordination number of a haem group?
6
What are the ligands in haem group?
4 nitrogen forming the porphyrin ring
1 oxygen
1 globin
Why is CO toxic?
CO also coordinately bonds. to the Fe²⁺, and bonds more strongly to Fe²⁺ than O₂. Stops O₂ from bonding to haemoglobin, so O₂ cannot be transported around the body
