15 - Transition Metals [SET 1] Flashcards
Where are transition metals found in the periodic table?
D block
What are transition metals?
D block elements that can form one or more stable ions with incompletely filled d-orbitals
Which d block period 4 elements are not transition metals?
Scandium and Zinc
How many electrons can the d orbital hold?
10
When ions are formed, which electrons are removed first?
The s electrons
Why is Scandium not a transition metal?
It only forms one ion, Sc3+, which has an empty d subshell
Why is zinc not a transition metal?
It only forms one ion, Zn2+, which has a full d subshell
How many stable oxidation states does Vanadium have?
4
What are the stable oxidation states of Vanadium?
II, III, IV, V
What do transition metals have?
Variable oxidation states
What conditions must be met to form a compound of complex with an ion of a certain oxidation number?
The energy given out when the ion forms a compound or complex needs to be greater than the ionisation energy
How do transition metals form ions?
By loosing electrons from their 4s and 3d subshells
When does the energy released when an ion forms a complex or compound increase?
When the ionic charge increases.
What are complex ions?
Metal ions surrounded by datively covalently bonded ligands
What is a ligand?
An atom, ion or molecule which donates a pair of electrons to a central metal atom or ion.
What are monodentate ligands?
Ligands with one lone pair
What are bidentate ligands?
Ligands with two lone pairs
What are multidentate ligands?
Ligands with more than two lone pairs
What are examples of monodentate ligands?
H2O, NH3, Cl-
What is an example of a multidentate ligands?
EDTA 4-
What is the name for water in a complex?
Aqua
What is the name for a hydroide group in a complex?
hydroxo
What is the name for ammonia in a complex?
Ammine
What is the name for chloride in a complex?
Chloro
How many colours traditionally make up white light?
7
Why are transition metal complexes coloured?
Electrons split into two energy levels when ligands attach. If an electron absorbs light, it can move to a higher energy level, and the light reflected is the colour seen
With 6 ligands, what shape is a complex?
Octahedral
With 4 ligands, what shape is a complex?
Tetrahedral or square planar
With 2 ligands, what shape is a complex?
Linear
What is an example of a linear complex?
Tollen’s reagent
What is cis-platin?
An anti-cancer drug which has a square planar shape
What does a cis- prefix indicate?
That the identical ligands are next to each other
What does a trans- prefix indicate?
That the identical ligands are opposite each other
How does cis-platin kill cancer cells?
It forms a bond between the two strands of DNA which prevents them from separating, and therefore prevents replication
How is trans-platin different to cis-platin?
It is toxic and much less effective at targeting cancer
Why does reducing the number of ligands increase stability?
The system becomes more disordered and there is an increase in ∆S system
What causes the greatest increase in stability?
Exchanging a monodentate ligand for a multidentate ligand
How is Fe held in haemoglobin?
By forming dative bonds with four nitrogens in the structure, in a square planar
What else is bonded to the Fe in haemoglobin?
Globin (a protein) and Oxygen
Why is carbon monoxide poisonous?
Because the dative bond between carbon monoxide and haemoglobin is stronger than with oxygen, so any CO breathed in will bins with the haemoglobin and not break easily
What is the equation for the reaction between aqueous NaOH and copper(II) sulfate solution?
[Cu(H2O)6]2+ + 2OH- —> [Cu(H2O)4(OH)2] + H2O
What colour is [Cu(H2O)4(OH)2]?
Blue precipitate
What is the equation for the reaction between aqueous ammonia and copper (II) sulfate?
[Cu(H2O)6]2+ + NH3 —-> [Cu(H2O)4(OH)2] + 2NH4+