5.3.1 Transition Elemtns and 5.3.2 Qualitative Analysis
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Define a transition element
A d block element that forms atleast 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 the 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 mp and bp shiny good conductor of heat and electricity
What are the characteristic chemical properties of transition metals?
Variable oxidation states take part in any redox reactions Coloured compounds / ions in solution Good catalysts Form complex ions
In potassium manganate (Vll), 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 (4)?
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 o 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 does the coordination number indicate
The number of coordinate bonds formed between the metal ion and its ligands
What is a mono/unidentate ligand
a ligand that forms one coordinate 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
Cl- H2O NH3 CN-
Name the most common bidentate ligand
ethane-1,2-diamine
How many coordinate bonds does EDTA 4- 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
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