Transition Metals Flashcards
Describe what a d-block transition metal is
The d-block transition metals are metals with an incomplete d subshell in at least one of their ions.
Describe the anomalies in the Transition metals which do not abide by aufbau
The filling of the d orbitals follows the aufbau principle, with the exception of chromium and copper atoms.
Describe why these anomalies copper and cobalt can exist
These exceptions are due to the special stability associated with the d subshell being half-filled or completely filled
From the first row of the transition metals, their ions describe the electrons lost in order of subshells eg 4s and 3d
When atoms from the first row of the transition elements form ions, it is the 4s electrons that are lost first rather than the 3d electrons.
When is an element said to be in particular oxidation state
An element is said to be in a particular oxidation state when it has a specific oxidation number.
How can the oxidation state be determined for
-uncombined elements
-ions containing single atoms
The oxidation number can be determined by the following:
uncombined elements have an oxidation number of 0
ions containing single atoms have an oxidation number that is the same as the charge on the ion
in most of its compounds, oxygen has an oxidation number of −2
in most of its compounds, hydrogen has an oxidation number of
+1
the sum of all the oxidation numbers of all the atoms in a neutral
compound must add up to zero
the sum of all the oxidation numbers of all the atoms in a polyatomic ion must be equal to the charge on the ion
A transition metal can have different…
A transition metal can have different oxidation states in its compounds.
Describe what could be different about compounds of the same transition meta in different oxidation states
Compounds of the same transition metal in different oxidation states may have different colours.
Describe the definition of oxidation and reduction in terms of oxidation states
Oxidation can be defined as an increase in oxidation number. Reduction can be considered as a decrease in oxidation number
Describe how oxidation or reduction can be identified in transition metal ions
Changes in oxidation number of transition metal ions can be used to determine whether oxidation or reduction has occurred.
Describe how oxidation states determines the type of agent a compound can be
Compounds containing metals in high oxidation states are often oxidising agents, whereas compounds with metals in low oxidation states are often reducing agents.
Describe what a ligand is and how they bond to a central atom or ion
Ligands may be negative ions or molecules with non-bonding pairs of electrons that they donate to the central metal atom or ion, forming dative covalent bonds.
Describe the classes of ligands
Ligands can be classified as monodentate, bidentate, up to hexadentate.
Ligands:
Mono-dentate:neutral H2O, NH3,CO. CHARGED- OH,F,CL,BR,I,CN
BIDENTATE-H2NCH2CH2NH2
What is the coordination number
The total number of bonds from the ligands to the central transition metal is known as the coordination number.
How do you name transition metal complexes?
central metals that obey the normal IUPAC rules
copper (cuprate) and iron (ferrate)(for negative complex ions)
ligands, including water, ammonia, halogens, cyanide, hydroxide, and oxalate for
-Metal name ends in ate if it is negative complex
-water becomes OH2 instead and is called aqua, ammonia to ammine.
# if the transition metal doesn’t end in ate it is either positive or neutral
#the O.S of the TM and ligands will add together to give the overall charge
What happens to the d orbitals in a complex of a transition metal
In a complex of a transition metal, the d orbitals are no longer degenerate
What causes the splitting of d orbitals and the affect this has on the energy on d orbitals
Splitting of d orbitals to higher and lower energies occurs when the electrons present in approaching ligands cause the electrons in the orbitals lying along the axes to be repelled.
Describe what strong field ligands and weak field ligands are
Ligands that cause a large difference in energy between subsets of d orbitals are strong field ligands. Weak field ligands cause a small energy difference.
The order of ability to split d orbitals is called… series
Ligands can be placed in an order of their ability to split d orbitals. This is called the spectrochemical series.
How can the colours of transition metals be explained
Colours of many transition metal complexes can be explained in terms of d-d transitions.
What happens when light is absorbed and electrons in a lower energy d orbital take that light in
Light is absorbed when electrons in a lower energy d orbital are promoted to a d orbital of higher energy.
Describe how a complementary colour is observed
If light of one colour is absorbed, then the complementary colour will be observed.
Describe how the electromagnetic spectrum is observed
Electrons transition to higher energy levels when energy corresponding to the ultraviolet or visible regions of the electromagnetic spectrum is absorbed.
What can transition metals and their compounds act as?
Transition metals and their compounds can act as catalysts.
Describe a heterogeneous catalyst
Heterogeneous catalysts are in a different state to the reactants.
Describe a heterogeneous catalyst
Heterogeneous catalysis can be explained in terms of the formation of activated complexes and the adsorption of reactive molecules onto active sites. The presence of unpaired d electrons or unfilled d orbitals is thought to allow activated complexes to form. This can provide reaction pathways with lower activation energies compared to the uncatalysed reaction.
Describe a homogeneous catalyst
Homogeneous catalysts are in the same state as the reactants.
Describe homogeneous catalysis
Homogeneous catalysis can be explained in terms of changing oxidation states with the formation of intermediate complexes.
