transition metals Flashcards
where are transition metals found
d block
what are transition metals
d block elements that can form one or more stable ions with incompletely filled d orbitals
what d block elements are not transition metals
scandium and zinc
why isn’t scandium a transition metal
scandium only forms one ion Sc³⁺ which has a empty d sub shell
it has configuration [Ar]3d¹4s² when it loses three electrons it has configuration of [Ar]
why isnt zinc a transition metal
zinc only forms Zn²⁺ which has a full d sub shell
its configuration is [Ar] 3d¹⁰4s² when it loses two electrons it has a full 3d subshell
transition metals have variable … numbers
oxidation
transition metals can have variable oxidation numbers because they form multiple …
stable ions
what needs to happen to form a compound or a complex containing an ion with a certain oxidation number
energy given out when complex is formed has to be bigger than the energy taken to remove outer electrons and form the ion (the ionisation energy)
transition metals form ions from losing electrons from which subshells
4s and 3d
why does it take similar amounts of energy to remove an electron from 4s sub shell and the 3d sub shell
because the 4s sub shell and the 3d sub shell have similar energy levels
what happens to the energy released when ions form complexes with increasing ionic charge
increases
what is a complex ion
metal ion surrounded by dative covalently (coordinately) bonded ligands
what is a ligand
a atom ion or molecule that donates a pair of electrons to a central metal atom or ion
what must a ligand have
at least one lone pair of electrons or it wont have anything to form a dative covalent bond with
ligands with one lone pair are called
monodentate
eg. H₂O: :NH₃ :Cl ⁻ :OH⁻
ligands with two lone pairs are called
bidentate
example of bidentate ligand
1,2-diaminoethane
NH₂CH₂CH₂NH₂
which ligands can form two dative covalent bonds with a metal ion
bidentate ligands
ligands with more than two lone pairs are called
multidentate
EDTA⁴⁻ has six lone pairs what ligand is it and how many dative covalent bonds can it form
hexadentate ligand/multidentate
and can form six dative covalent bonds with metal ion
what does haemoglobin do
transport oxygen around the body
what metal complex is haemoglobin
iron(II)
what type of ligand is haemoglobin
a multidentate ligand called a haem group
what is a haem group made up of
a ring containing 4 nitrogen atoms with iron at the centre
the overall charge on a complex ion is its
oxidation number
where would you put the charge on a complex ion
outside the square brackets
oxidation number of the metal ion =
total oxidation number - sum of the charges of the ligand
work out the charge of the metal ion iron in [Fe(CN)6]⁴⁻
total oxidation number = -4
CN⁻ ligand charge = -1
iron oxidation number = -4 - (6 x -1 ) = +2
what is the coordination number
number of dative covalent (coordinate) bonds formed with central metal ion
what are usual coordinate numbers
6 and 4
if a ligand is small what is the usual coordinate number
6
if a ligand is larger what is the usual coordinate number
4
why are the ligands positioned as far away from each other
because bonding electrons in dative covalent bond of a complex repel each other
what is the shape and bond angle in six fold coordination
octahedral shape and all bond angles are 90
what is th shape and bond angle in four fold coordination
tetrahedral shape bong angles are 109.5
what is the other occasional four fold coordination
square planar where bond angles are 90
eg cis-platin
cis/trans isomerism a form of
E/Z isomerism
which shape complex ions can show cis/trans isomerism
square planar and octahedral
what happens to the groups in cis isomers
they are on the same side
what happens tot he groups in trans isomers
same groups opposite each other
what metal complex is cis-platin
platinum(II)
what ligands are on cis-platin
two chloride ions and two ammonia molecules
what shape is cis-platin
square planar and so has bond angles of 90
what is cis-platin used for
anti cancer drug
why cant trans-platin be given to patients being treated for cancer
its toxic
what happens to 3d orbital when ligands bond to the central ion
3d orbital splits into two different energy levels
what orbitals do electrons tend to occupy
the lower orbitals
what do electrons need to jump up to higher electron orbitals
energy equal to the energy gap
where do electrons get the energy to jump up to higher orbitals
from visible light
for larger energy gaps does the frequency of light absorbed increase or decrease
increase
what affects the size of the energy gap
central metal ion
the central metal ions oxidation number
the ligands
coordination number
what happens to the rest of the frequencies of light that are not absorbed
they are transmitted or reflected
what do the transmitted or reflected frequencies of light do
combine to make the complement of the colour of the absorbed frequencies
from red to purple light what happens to the frequency
frequency increases
what is the complimentary of red
cyan
what is the complementary of yellow
blue
what is the complementary of green
magenta
what is the complementary of cyan
red
what is the complementary of blue
yellow
what is the complementary of magenta
green