last section Flashcards
properties of transition metals
- hard
- high melting points
- solids
- conduct heat and electricity
- variety of oxidation states
- readily lose electrons to form stable cations
properties of transition metals: d-orbitals
there are five d-orbitals: each can contain up to 2 electrons
(10 members of each transition series)
how many different d orbitals are there
5 orbitals of equivalent energy
- four look like clovers
the dz² orbital is a combination of lobes and doughnuts
Hund’s Rule
electrons fill empty orbitals before pairing
ions in the lighter d-block elements …
form colorful hydrated ions that are stable in water
ions in period 5 and 6 …
are unstable, react readily with oxygen from the air
what elements are part of the “platinum metals”
ruthenium, osmium, iridium, palladium, platinum
what is the significance of the platinum metals
with difficulty they form simple cations that are stable in water
they not not form stable oxyanions
when in bonding in simple metals with transition metals ionic
in lower oxidation states
when is the bonding in simple metals with transition metals covalent
in higher oxidation states
on heating oxygen reacts with all of the transition elements except
palladium
platinum
silver
gold
anhydrous halides
of each of the transition elements can be prepared by the direct reaction of the metal with halogens
in general what does fluorine usually form halides with
transition elements in the highest possible oxidation state
what is the general approach to synthesis aq. solutions of halides of 1st transition series
reaction of salts with hydrohalic acids
most of the halide series also dissolve in acidic solutions to give
halide salt and hydrogen gas
Mn(s) + 2HCl(aq) ⟶ MnCl2(aq) + H2(g)↑
what does the polarity of M-X bonds with transition metals depend on
electronegativities of the elements and oxidation state of the metal
what forms when a soluble hydroxide is added to an aqueous solution of transition metals ions
gelatinous precipitate
how can insoluble carbonates be formed
adding a soluble carbonate salt to a solution of transition metal salt
carbonates react with acids to form
metal salts
carbonates decompose on heating to form
transition metal oxides
coordination sphere
the central metal ion or atom plus its attached ligands
coordination number of the central metal
the number of donor atoms bonded to it
inner sphere and outer sphere complexes
Inner sphere complexes are electrically neutral without need for external counterions
Outer sphere complexes require counterions which exist outside of the coordination sphere of the central metal ion
what are the different ways that a ligand can be classified
- charged or neutral ligands
- denticity (number of Lewis basic atoms)
- hard or soft bases
common neutral ligands include:
water
ethylenediamine
tetrahydrofuran
ammonia
common anionic ligands include
cyanide
hydride and halides
perchlorate
nitrate
hydroxide
monodentate denticity
ligands that connect with the central metal through one atom
what are polydentate ligands
molecules that contain more then one Lewis base atom and coordinate to the central metal in more complex fashions
lanthanides
silvery metals, inaccuratelt called, rare earth metals despite being more abundant in the earth’s crust than eg, lead
actinides
all radioactive
have similar chemical and physical properties
applications of lanthanides
- security
- displays, televisions, smartscreens
- fibre optics and telecomunications
- lighting, LEDs, lasers
coordination sphere
transition metals form bonds with multiple ligands to form a coordination sphere
coordination spheres can consist of different numbers and geometeries of ligands depending on
the metal ion and the size/shape of the ligands
coordination number
the number of M-L bonds around a metal
ligand-ligand repulsion
limits the number of bonds made, as in general metal ions try to make bonds with as many ligands as possible
for transition metal complexes what is the main contributor to determining the geometry around the central metal
coordination number
what is the coordination number of a linear molecule
2
what is the coordination number of a trigonal planar molecule
3
coordination number three
rare coordination number
usually due to bulky ligands causing steric hindrance around the metal centre
- 120 degree angles
coordination number of four
there are two major options available:
- tetrahedral
- square planar
tetrahedral
- very common for d0 and d10 transition metals
square planar
fairly uncommon and found only in d8 metal ions
- 90 degree angles
Which is the name of [Cr(H2O)4Cl2]Cl
Tetraaquadichlorochromium(III) chloride
According to crystal field theory, which of the d orbitals are lowered in energy
(relative to a spherical field) in a tetrahedral ligand field, Td?
dz²
What is the coordination geometry of [Ag(NH3)2]+
octahedral
