1.3 transition metals Flashcards
what block are the transition metals
d
do transition metals have full d subshells?
no, only partially filled
which principle does the filling of d orbitals follow
the aufbau
what two transition metals are an exception for filling up following the aufbau principle, and why
chromium and copper
they have a special stability associated with the d subsjell being half filled or completely filled
which electrons are lost if atoms from the first row of transition metals form ions
the 4s electrons. not the 3d!
when is an element said to be in a particular oxidation state
when it has a specific oxidation number
what is the oxidation number of uncombined elements
0
what is the oxidation number of ions containing single atoms
one that is the same as the charge on the ion
what is the usual oxidation number of oxygen
-2
what is the usual oxidation number of hydrogen
1
what must the sum of all the oxidation numbers of all the atoms in a neutral atom add up to
0
what must the sum of all the oxidation numbers of all the atoms in a polyatomic ion be equal to
the charge on the ion
can a transition metal have different oxidation states in its compounds
yes
can the compounds of the same transitio nmetal in different oxidation states have different colours
yes they may
what can oxidation be defined as
an increase in oxidation number
what can reduction be considered as
a decrease in oxidation number
what can the changes in oxidation number of transition metals be used to determine
whether oxidation or reduction has occurred
what compounds containing metals are often recognized as oxidising agents
those with high oxidation states
which compounds containing are often recognized as reducing agents
those with low oxidation states
what are ligands
- negative ions
- molecules with non bonding pairs
how can ligands be classified
monodentate, bidentate, hexadentate
is it possible to deduce the ligand classification from a formula or structure of the ligand or complex
unfortunately yes
what is the coordination number
the total number of bonds from the ligands to the central transition metal
when are d orbitals no longer degenerate
in a complex of a transition metal
when does the splitting of d orbials to higher and lower energies occur
when the electrons present in the approaching ligands cause the electrons in the orbitals lying along the axes to be repelled
what are strong field ligands
ligands that cause a large difference in energy between subsets of d orbitals
what are weak field ligands
ligands that cause a small difference in energy between subsets of d orbitals
how can ligands be placed
in order of their ability to split d orbitals
what is the spectrochemical series
the order that ligands are placed according to their ability to split d orbitals
how can the colours of many transition metal complexes be explained
in terms of d-d transitions
when is light absorbed
when electrons in lower energy d orbital are promoted to d orbital of higher energy
when is the complementary colour observed
when one light of one colour is absorbed
when light of one colour is absorbed, what is observed
the complementary colour
when do electrons transition to higher energy levels
when energy corresponding to the ultraviolet or visible regions of the electromagnetic spectrum is absorbed
can transition metals act as catalysts
yes
are heterogenous catalysts in different states to the reactants
yes
how can heterogenous catalysts be explained
in terms of the formation of activated complexes and the adsorption of reactive molecules onto active sites
what is the presence of unpaired d electrons or unfilled d orbitals thought to allow
activated complexes to form
what can the formation of activated complexes provide
reaction pathways with lower activation energies compared to the uncatalysed reaction
are homogenous catalysts in the same or different state as the reactants
same
how can homogenous catalysts be explained
in terms of changing oxidation states with the formation of intermediate complexes
