Atomic Orbitals and Transition Metals Flashcards
Heisenberg’s uncertainty principle
you can probably say a region of space that an electron would most likely be found in
pauli exclusion principle
orbitals can only hold 2 electrons and they must be spinning in opposite directions
aufbau principle
electrons will fill the orbitals that occupy the lowest energy level before the further away ones
hund’s rule
when degenerate orbitals are available, these are filled singly before pairing up to fill orbitals
principle quantum number (n)
shell of electron
second quantum number (l)
orbital of electron (0,1,2,3)
third quantum number (m)
orientation in space of the orbital that the electron is found in
fourth quantum number (s)
spin of the electron (+1/2 or -1/2)
how many electrons can s orbitals hold?
2
how many electrons can p orbitals hold?
6
how many electrons can d orbitals hold?
10
shape of s orbitals
spherical
shape of p orbitals
dumb bell shaped
VSEPR
Valence Shell Electron Pair Replusion
what is VSEPR for?
to determine how many electron pairs are surrounding the central atom and therefore how they are oriented in space as the electron pairs repel eachother
steps of VSEPR
- how many outer electrons on central atom?
- how many electrons present due to bonding pairs?
- for polyatomic ions, how many electrons gained or lost?
- divide total by 2 to determine no of pairs that surround the atom
what does the repulsion of electron pairs surrounding central atom result in?
different shapes for molecules and polyatomic ions
electron pairs and the arrangement of the electron pairs
2- linear 3- trigonal planar 4- tetrahedral 5- trigonal bipyramidal 6- octrahedral
strength of repulsion of electron pairs
bonded- bonded (least repulsion), bonded- lone, lone-lone (greatest repulsion)
relationship between electron configuration and ionisation energies
the more stable the electron configuration, the higher the ionisation energy
when is a subshell most stable?
when it is filled or half filled
transition metal
metal with an incomplete d shell
when transition metals lose electrons to form ions, which subshell are electrons lost from first?
4s
why aren’t zinc and scandium transition metals?
their d subshells aren’t either filled or half filled
oxidation numbers for atoms in elements
0
sum of oxidation numbers in compounds
0
sum of oxidation numbers in ions
equal to the charge on the ion
oxidation number of F
-1
oxidation number of O
-2
oxidation number of H
+1
oxidation number of Cl
-1
if oxidation number increases in a reaction
element is oxidised
if oxidation number decreases in a reaction
element is reduced
compounds containing metals in high oxidation states
oxidising agents
compounds containing metals in low oxidation states
reducing agents
dative covalent bond
one atom is supplying both electrons for the covalent bond
can compounds of the same transition metal but in different oxidation states have different colours?
yes
complex
consists of a central metal ion surrounded by a number of negatively charged ions or neutral molecules possessing lone pair of electrons , surrounding are ligands
ligands
electron donors, donate non bonding electrons into unfilled metal orbitals to form dative covalent bonds
monodenate
forms a single dative covalent bond with central metal ion
bidenate
forms two dative covalent bond with central metal ion
hexadenate
forms six dative covalent bond with central metal ion
coordination number
number of bonds from ligands to central metal ion
naming complex ions using iupac rules
- number of ligands using mono-, bi-…
- identify ligands in alphabetical order sing ending -o for - ions
- name central metal ion, if + or neutral= english name but if - = latin name with ending -ate
colour in transition metal complexes
in split d-d orbitals, electrons in lower energy d orbitals can absorb energy and move to higher energy d orbitals- if energy absorbed in d-d transitions is in visibile part of electro spectrum, colour of transition metal will be complemetary colour of absorbed colour
splitting of d orbitals
electrons in degenerate d orbitals are replled by the electrons in the ligand molecules- orbitals have higher enegy that d orbitals that lie between axes and are no longer degenerate
what does energy difference between different subsets of d orbitals depend on?
the ligand and its position in spectrochemical series
heterogenous catalysts
different physical state to the reactants in catalysed reactions
homogeneous catalyst
same physical state to the reactants in catalysed reactions
strong field ligands
cause the greatest splitting of d orbitals and d-d transitions are likely to occur in UV region- 200 to 400nm
weak field lignads
d-d transitions are likely to occur in visible region, complexes are likely to be coloured
why are transition metals good catalysts?
- transiton metal atoms on surface of catalyst active sites form weak bonds with reactant molecules using partially filled or empty d orbitals forming intermediate compounds which weakens covalent bonds within the reactant molecules- provides an alternative pathway with lower activation energy increasing the rate of reaction
- having variable oxidation states allow the transition metal to provide an alternative pathway with a lower activation energy
