Inorganic Chapter 4: Transition Metals Flashcards
Where are transition metals found in the periodic table?
The d-block
What causes the special chemical properties of transition metals?
The partially filled d-block
What 2 metals in period 4 aren’t transition metals?
Sc and Zn - Scandium forms an ion with an empty d sub-level, while Zinc forms an ion with a full d sub-level.
Which electrons are lost first when you have a full 4s orbital and a partially filled 3d orbital?
The s orbitals go first, then the d orbitals.
What physical properties do transition metals generally share?
High density
High melting/boiling points
Similar ionic radius
What are the four main special properties of transition metals?
Can form complex ions
Can form coloured ions
Good catalysts
Can exist in variable oxidation states
What is a complex ion?
A metal ion surrounded by ligands
What is a ligand?
An atom or molecule that donates a pair of electons to a central transition metal ion, forming a co-ordinate bond.
What is the coordination number?
The numer of coordinate bonds formed with the central metal ion.
What shape is formed when a complex ion has 6 coordinate bonds?
Octahedral
What shape is formed when a complex ion has 4 coordinate bonds?
Tetrahedral or Square planar - Square Planar is the exception, only occurs sometimes e.g. Cisplatin
What complex ions form linear shapes?
Silver-based complexes e.g. [Ag(NH3)2]+
What are small ligands that can form 6 coordinate bonds on an ion?
H2O, NH3
What are some larger ligands that can only form 4 coordinate bonds on an ion?
Cl-
What does the overall charge on a complex represent?
Its total oxidation state
How can you work out the oxidation state of the central metal ion in a complex?
Total oxidation state - oxidation states of all the ligands
Why does a ligand need to have at least 1 lone pair?
Otherwise it has nothing to donate
What is meant by a monodentate ligand?
The ligand can only form 1 coordinate bond - only has 1 lone pair
What is meant by a multidentate ligand?
The ligand can form more than 2 coordinate bonds - has more than 2 lone pairs
What is a Bidentate ligand?
A ligand that has 2 lone pairs - can form 2 coordinate bonds
What is an example of a naturally-occuring complex ion?
Haemoglobin
Why does Carbon monoxide cause oxygen poisoning?
Oxygen binds to the haemoglobin as a lingand, but CO does too, and it’s a strong ligand, so won’t get displaced by oxygen molecules on the haemoglobin.
What type of isomerism can complex ions show?
Optical isomerism
Cis-Trans Isomerism
How do octahedral complexes show Cis-Trans isomerism?
The Trans version has the two odd ligands opposite each other, while the Cis version has them next to each other.
How do different coloured ions form?
The 3d sub-level is split into two energy levels when ligands bond to a central ion. There is an energy gap between the lower and upper levels, and the energy needed to promote an electron to the higher level comes from visible light, thereby determining which light wavelengths are absorbed.
What formula is used to calculate the energy gap?
ΔE = hv = hc/λ
v = frequency of light absorbed (hz)
h = planck’s constant (J/s)
c = speed of light (m/s)
λ = wavelength of light absorbed (m)
What is the use of coloured ions?
You can identify ions via their colours
What are the three factors that affect the colour of an ion?
Oxidation state
Coordination number
Changes in ligand
How can you use spectroscopy to determine concentration of transition metal ions?
White light is shone through a filter, which is chosen to only let through the colour of light absorbed by the sample. This light then passes to a colorimeter, which calculates how much light was absorbed by the sample. This measurement can then be used to calculate concentration using a calibration curve.