18 - Transition elements Flashcards
What is a transition element?
A d-block element that forms an ion with an incomplete d sub-shell
Which elements in d-block aren’t transition metals?
Scandium and zinc
Why is scandium not a transition metal?
Forms Sc 3+ meaning the d sub-shell is empty
Why is zinc not a transition metal?
Only forms Zn 2+ so it has only full d-subshells
What are the exceptions to the spin pair distribution of transition metals? Explain
Chromium and copper only have 4s^1 and have an extra one in 3d instead
What is different about the appearance of different ions for the same element?
They have different colours
Why do ions actually have colours?
Light is absorbed and we see the colours not absorbed
What happens to white solids when they form solutions?
The solution is always colourless
What are the 3 properties of TRANSITION metals?
Different oxidation states
Act as heterogeneous catalysts
Different colours
What is the contact process and what is the catalyst?
2SO~2 + O~2 –> 2SO~3
With V~2 O~5 catalyst
What is the catalyst for reacting zinc with an acid?
Cu 2+ catalyst
Define ligand
A ligand is a molecule or ion that can donate a pair of electron to form a dative covalent bond with a transition metal
What is the condition to be a ligand?
Must have lone pairs of electrons in the outer energy level. These are used to form co-ordinate bonds with the metal ion.
All ligands are lone pair donors
Define complex ion
A transition metal ion bonded to one or more ligands by dative covalent bonds
What is coordination number?
Number of dative bonds to central ion
What is a monodentate ligand?
Where only one atom in the ligand has a lone pair
It only bonds to the central ion with one bond
What are the 6 main ligands and what are their oxidation numbers?
H~2 O is 0
NH~3 is 0
SCN (thiocyanate) is -1
CN (cyanide) is -1
Cl- is -1
OH- is -1
How do you write the formula of a complex ion?
e.g. Copper(II) ion with one OH and 5 water ligands.
A copper(II) ion with one OH and 5 water ligands is:
[Cu OH (H~2 O)~5] +
The +ve charge is the sum of all charges in complex ion
When there are 4 ligands, what shape is formed?
Tetrahedral
What is the exception to the tetrahedral, 4 ligand idea?
Nickel, platinum, palladium and gold make a square planar shape instead
What are Cis and Trans complex ions?
When you have multiple ligands of 2 different types of molecule
Trans is where the same group ligands are opposite each other in the shape
Cis is where this isn’t true
What is Cis-platin?
A very effective cancer drug which binds to DNA
What are bidentate ligands?
Ligands that form 2 different dative bonds with the central ion
What is the name and charge of C~2 O~4?
Ethanedioate with a 2- charge
