Final not yet

- Transition metals and refractory metals (Cr, Mo, W).
- Wide oxidation states.
- Include:
Chromium (Cr) Molybdenum (Mo) Tungsten (W)
and Seaborgium (Sg).
GROUP VIB - INTRODUCTION
1) Overview:

1) Overview:
Tungsten:
• Lowest coefficient of thermal expansion
• High melting point
• Strength of tungsten are due
to strong covalent bonds
Highest
melting
point

2) Natural resouces:
Chromium
Crocoite (PbCrO4) Chromite (FeCr2O4)

Molybdenum
Molybdenum:
Wulfenite
( PbMoO4 )
Powellite
(CaMoO4 )
Molybdenite
( MoS2)2

Wolframite
(Fe,Mn)WO4
Scheelite (
CaWO4),
Hübnerite
(MnWO4).
Tungsten :

GROUP VIB – PHYSICAL PROPERTIES
• White metal silver shiny
• Heavy metals
• Good electrical conductivity
 Thermal conductivity
• Highest melting point

GROUP VIB – PHYSICAL PROPERTIES
Chromium Molybdenum Tungsten
Atomic number 24 42 74
Electron configuration [Ar] 3d54s1 [Kr] 4d55s1 [Xe] 4f145d46s2
Melting point 1907°C 2622°C 3414°C
Boiling point 2671°C 4639°C 5555°C
Relative atomic mass 51.996 95.95 183.84
Key isotopes 52Cr, 53Cr and 54Cr 95Mo, 96Mo, 98Mo 182W, 184W, 186W

GROUP VIB – CHEMICAL PROPERTIES
• Sustained with air, moisture and carbon
dioxide
• Reacts with oxygen at high temperatures
4Cr (s) + 3O2 (g) → 2Cr2O3 (s) ( in 300oC, ∆Ho = -1141 kJ/mol )
2Mo (s) + 3O2 (g) → 2MoO3 (s) ( in 600oC, ∆Ho = -745 kJ/mol )
2W (s) + 3O2 (g) → 2WO3 (s) ( in 600oC, ∆Ho = -842 kJ/mol )

• Reacts with fluorine gas at room temperature
2Cr(s) + 5F2(g) → 2CrF5(s) [red]
• Chromium reacts with fluorine, F2, at 400°C and 200-
300 atm
Cr(s) + 3F2(g) → CrF6(s) [yellow]

2Cr(s) + 3F2(g) → 2CrF3(s) [green]
2Cr(s) + 3Cl2(g) → 2CrCl3(s) [red-violet]
2Cr(s) + 3Br2(g) → 2CrBr3(s) [very dark green]
2Cr(s) + 3I2(g) → 2CrI3(s) [very dark green]
. In high temperature, Cr, Mo, W react with others
halogen.

• React with non-metallic elements in high
temperature
W + N2 → WN2 ( 2000oC – 2500oC )
Mo + C → MoC ( > 800oC )
W + C → WC (> 1400oC )
• No effect with hydrogen

• React with water at high
temperatures
2Cr + 3H2O → Cr2O3 + 3H2
Mo + 2H2O → MoO2 + 2H2
W + 2H2O → WO2 + 2H2
• Chromium can dissolve in dilute solution of HCl
and H2SO4
Cr + 2HCl → CrCl2 + H2 ( Eo
Cr
2+
/Cr = -0.91V )
• Mo and W are not effective with HCl and H2SO4

W + 8HF +2HNO3 → H2WF8 + 2NO + 4H2O
Mo + Na2CO3 + 3NaNO3 → Na2MoO4 + 3NaNO2 + CO2

Ionic
Radius
0.87 Å Cr2+ coordination number = 6; low spin
0.94 Å Cr2+ coordination number = 6; high spin
0.755 Å Cr3+ coordination number = 6
In coordination compound

• The metal also forms many compounds of intense
colour:
Chromates (e.g. Na2CrO4, PbCrO4) – Yellow
sodium chromate
Dichromates (e.g K2Cr2O7) ............. Orange-
red
potassium Dichromate

Chromic acid, CrO3 .......................... Red
Chromic acid
 Chromium(III) oxide, Cr2O3 .............. Green
Chromium(III) oxide

GROUP VIB – BIOLOGYCAL ROLE
• Chromium is trace element
• Biologically active form of chromium (III) might
play a role in the insulin signaling pathway
Chromium

Molybdenum
• The reaction that nitrogenase enzymes perform is:
N2 + 8H+ +8e- + 16ATP + 16H2O → 2 NH3 + H2 + 16 ADP + 16Pi
• Molybdenum is cofactor enzymes

• Human dietary intake and deficiency
 People deficient molybdenum are prone to
toxic reactions to sulfites in foods
 Molybdenum is also present within human
tooth enamel and may help prevent its decay.
 Pork, lamb, and beef liver, include green
beans, eggs, sunflower seeds, wheat flour,
lentils, cucumbers and cereal grain.

• Related diseases
 Congenital molybdenum cofactor deficiency
disease, seen in infants
 Neurological damage.

• Used by some bacteria, but not in eukaryotes
Tungsten
• Tungsten-using enzymes reduce carboxylic
acids to aldehydes.
• Tungsten has been studied as a biological
copper metabolic antagonist

GROUP VIB – APPLICATION IN LIFE
Chromium
• Metallurgy

 Dye and pigment
 Wood preservative
 Tanning
 Refractory material
 Catalysts

 Alloys
Molybdenum
 Used as a fertilizer for some plants
 Certain low voltage X-ray sources

Tungsten
 Hard materials
 Alloys
 Armaments
 Niche uses
 Gold substitution
 Electronics

GROUP VIB –GROUP VIB – CHROMIUM COMPOUNDS
• Chromium(II) oxide (CrO) is a black powder
• Hypophosphites may reduce chromium(III) oxide
to chromium(II) oxide
H3PO2 + 2 Cr2O3 → 4 CrO + H3PO4
• CrO is a basic oxide : CrO + 2HCl -> CrCl2 + H2O
• CrO is a reducing agent:
CrO + 4HNO3 c
𝒕 𝒐
Cr(NO3)3 + NO2 + 2H2O
Chromium(II)

GROUP VIB – CHROMIUM COMPOUNDS
Chromium(III) oxide
• One of principal oxides of chromium
Cr2O3
• Used as a pigment
• Occurs as the rare mineral eskolaite
eskolaite

• Chromium(III) oxide is amphoteric . It dissolves
in concentrated alkali to yield chromite ions.
Cr2O3 + 6HCl -> 2CrCl3 + 3H2O
Cr2O3 + 2NaOHc + 3H2O -> 2Na[Cr(OH)4]

Preparation
• Potassium dichromate with sulfur at high
temperatures
K2Cr2O7 + S
𝒕 𝒐
Cr2O3 + K2SO4
• Decomposition of chromium salts
(NH4)2Cr2O7
𝒕 𝒐
N2 + Cr2O3 + 4H2O

Chromium(VI) oxide
• Has chromium in its +6 oxidation state
• It is a dark red crystalline solid used
in cleaning glass

• Properties
 It is a strong oxidizing agent
 Can ignite alcohol
 Very toxic and irritates skin.
Chromium(VI) oxide

 Stronger oxidizing agent than chromate
 It dissolves in water to make chromic acid and
dichromic acid :
CrO3 + H2O -> H2CrO4
2CrO3 + H2O -> H2Cr2O7
 Reacts with strong bases to make chromates :
CrO3 + 2NaOH -> Na2CrO4 + H2O
Chromium(VI) oxide

• Preparation
Normally made by reacting sodium
chromate or potassium chromate with sulfuric acid
Chromium(VI) oxide

Application
Application
• Used to clean glass
• Used to plate chromate on
things.
• Reacts with metals to make a
metal chromate

Safety
• A dangerous hazard to the environment.
• A carcinogen and can cause mutations
• Chromium(VI) oxide is very toxic and irritating

Chromate and Dichromate
• Chromate, CrO4
2-, is a salt of chromic acid
• Yellow color in basic conditions.
A sample of potassium chromate

• Dichromate, Cr2O7
2-, is a salt of dichromic acid
• Strong orange color in acidic conditions.
A sample of potassium dichromate

• Strong oxidizing agent but it is a bad
precipitating agent.
• Used as a precipitating agent but it is a poor
oxidizing agent.
2CrO4
2− (s) + 2H+(aq) ⇌ H2O(l) + Cr2O7
2− (aq)
Kc=3.2×1014

• In acidic solution, the forward reaction is favored.
In basic solution, the reverse reaction is favored.
2Na2CrO4 + H2SO4 -> Na2Cr2O7 + Na2SO4 + H2O
Na2Cr2O7 + 2NaOH -> 2Na2CrO4 + H2O

6FeSO4 + K2Cr2O7 + 7H2SO4 -> 3Fe2(SO4)3
+ K2SO4 + Cr2(SO4)3 + 7H2O
• In acidic environment, salts of chromate and
dichromate are strong oxidizing agents:

GROUP VIIB - INTRODUCTION
1) Overview:
MANGANESE (Mn) TECHNETIUM (Tc) RHENIUM (Re)

GROUP VIIB – PHYSICAL PROPERTIES
• Manganese
- Hard metal
- Lustrous silver-blue
- Mp: 1519 / Bp: 2235
• Technetium
- Silver
- Mp=2430, Bp = 5150
• Rhenium
- Silver,
- Often encoutered as grey powder,
- Mp = 3459, Bp = 5900.

GROUP VIIB – PHYSICAL PROPERTIES
Sources
Manganese:
• The 5th most abundant metal in Earth’s crust.
• Pyrolusite (MnO2) and rhodochrosite
(MnCO3).
Pyrolusite (MnO2) rhodochrosite (MnCO3)

GROUP VIIB – CHEMICAL PROPERTIES
Technetium
• Uranium nuclear fuel reaction.
Rhenium
• In platinum ores.
uranium ores.
platinum ores
Sources
• Doesn’t accur in nature as
uncombined

Manganese
1. With O2:
3Mn(s) + 2O2(g) → Mn3O4(s)
2. With halogen:
Mn(s) + Cl2(g) → MnCl2(s)
Mn(s) + Br2(g) → MnBr2(s)
Mn(s) + I2(g) → MnI2(s)
- Moderately active metal

3. With nitrogen
3Mn(s) + N2(g) → Mn3N2(s)
5. In water, Mn slowly attack with H2O
6. In the first row of d-block metal, Mn has the
widest range of oxidation states, from II to VII.
4. React with Oxygen
4Tc + 7O2 → 2Tc2O7
4Tc + 7O2 → 2Tc2O7

GROUP VIIB – COMPOUNDS
Manganese (II) [3d5]
• Manganese (II) oxide MnO (green solid):
 Basic oxide
 Insoluble in water
 Soluble in acids, give pink solution, contain
[Mn(H2O)6]2+
Manganese (II) oxide

• Ion Mn2+ is easy to be oxidize.
• Mn(OH)2 : white, rapidly dark in air as the reaction
4Mn(OH)2 + O2 2Mn2O3 + 4H2O
• Mostly salts of Mn is soluble in water. MnSO4 is very
stable, MnPO4 and MnCO3 are sparingly soluble.
Manganese (II) [3d5]
→

• Manganese (III) oxide Mn2O3
MnO2 |1070K| Mn2O3
• Ion Mn3+ is less unstable in the presece of high
concentration of Mn2+ or H+ ion
2Mn3+ + 2H2O Mn2+ +MnO2 + 4H+
Manganese (III) [3d4]
→
→

• Manganese dioxide MnO2
 Inert in most acids except when heating, but not
dissolve to give Mn4+ (cause of the oxidizing
characteristic)
MnO2 + 4HCl MnCl2 + Cl2 +2H2O
• With H2SO4 in 110°C:
2MnO2 + 2H2SO4 2MnSO4 + O2 + H2O
+ With KOH in high temperature
4KOH + O2 + 2MnO2 2K2MnO4 + 2H2O
Manganese (IV): [3d3]
→
→
→

• The only oxohalide is MnOCl3
• In moist air, MnOCl3 hydrolyses to [MnO4]3-
• Salt of [MnO4]3- is blue and moisture-sensitive and
easily react with H+ even H2O
2[MnO4]3- + 2H2O [MnO4]2- + MnO2 + 4[OH]-
3[MnO4]3- + 8H+ [MnO4]- + 2MnO2 + 4H2O
Manganese (V) [3d2]
→
→

• Ion MnO42- have deep green color and is unstable
in acid medium, even in H2CO3:
3MnO42- + 4H+ 2MnO4- + MnO2 + 2H2O
• K2MnO4 is a powerful oxidizing agent, usually
used in organic chemistry experiment.
Manganese (VI): [3d1]
→

Most common is KMnO4: purple, strong oxidizing
4MnO4- + 4H+ 3O2 + MnO2 + 2H2O
Manganese (VII): [3d0]
→

• Oxide:
* Re2O7 is a yellow volatile oxide, hygroscopic compound
It dissolves in water as the reaction:
Re2O7 + H2O 2HReO4
• Halogenide:
ReCl5 + 3Cl2O ReO3Cl + 5Cl2
Tc2O7 + 4HF 2TcO3F + H3O+ + [HF2]-
Compound of Technetium and Rhenium
→
→
→

GROUP VIIB –
The equilibrium constants for the formation od
Mn(II) complexes are relatively low as Mn2+ ion
has no ligand field stabilization energy. However,
chelating ligand (ox, en, EDTA4-), form complexes
isolable form aqueous solution. Some ex: [MnX4]2-,
[MnCl6]4- (salt of Na and K).
Only very strong ligand fields give rise to spin
pairing as in the ion [Mn(CN)6]4- and [Mn(CNR)6]2+
which have only one unpaired electron.
Mananese (II):
Coordination compound

GROUP VIIB –
Complexes are probably important in
photosynthesis, where oxygen evolution depend
on Mn.
Mn (III) and Mn (IV)
Coordination compound

GROUP VIIB – Coordination compound
In HCl solution, ReO4- is reduced by
hypophosphite, partically to the chloro complexe
ion [ReCl6]2- partically to [Re2Cl8]2- ion.
Technetium and Rhenium

GROUP VIIB – APPLICATION IN LIFE
• Essential element in all living things.
Many type of enzyme contain Mn
• In human body:
+ Our body contain about 12 mgs of Mn.
+ We need to take 4 mgs Mn per day, from nuts, bran,
wholegrain cereals, tea and parsley.
+ Without Mn, bones grow spongier and break more
easily.
+ Essential for utilisation vitamin B1.
Manganese

Manganese

• The gamma – gray Tc is widely used for medical
diagnostic studies.
• Corrosion inhibitor for steel.
• Using limited to close systems as Te radio.
Technetium

• Used for oven filaments and x-ray machines.
• Used as an electrical contact material.
• Used in nickel alloys to make single-crystal
turbine blades.
Rhenium

• In steel production :
 Steel with 1% Manganese : stronger, improve
workability and resistance to wear.
 Steel with 13% Manganese : very strong and
used for railway, prison bar…
• MnO2: used as catalyst, a rubber addition and
to decolourise glass that is green by ion
impurities.
• MnSO4: make a fungicide.
• MnO: powerful oxidizing agent used in
quantitative analysis.
• Used in water purification and economical
bleaching.
Manganese

• MnO2: used as catalyst, a rubber addition and to
decolourise glass that is green by ion impurities.
• MnSO4: make a fungicide.
• MnO: powerful oxidizing agent used in
quantitative analysis.
• Used in water purification and economical
bleaching.
Manganese

Iron (Fe) Cobalt (Co) Nickel (Ni)
GROUP VIII - INTRODUCTION
1) Overview:
Ruthenium (Ru) Rhodium (Rh) Palladium (Pd)
Osmium (Os) Iridium (Ir) Platinum (Pt)
Platinum
Group
Metals
(PGMs)

1) Overview:
Iron:
• Fourth most abundant element in the
Earth’s crust
• 3 allotropes of iron is: α-iron (alpha-
iron); γ-iron (gamma-iron); and δ-iron
(delta-iron).
• Iron is used since prehistoric ages.

1) Overview:
Cobalt:
• The name in German is ‘kobalt’, which is
goblin.
• It is the 30th most abundant in crustal
rocks.

1) Overview:
Nickel:
• Is frequently used in coinage in nickel-
copper alloys.
• It is the 22nd most abundant in crustal
rocks.
• Raney Nickel, an alloy of Aluminum
and Nickel, is an important catalyst in
organic chemistry.

1) Overview:
Platinum Group Metals (PGMs)
• PGMs are often used in jewelry
• Catalytic prperties of PGMs are well-known

1) Overview:
Platinum Group Metals (PGMs)
• Catalytic properties are important in organic chemistry

Iron:
Hematite (Fe2O3) Magnetite (Fe3O4)
Limonite (Fe,Ni)O(OH) Siderite (FeCO3)

Cobalt:
Cobaltite (CoAsS) Skutterudite ((Co,Ni,Fe)As3)
Erythrite (Co3(AsO4) 8H2O)

Nickel:
Garnierite
(Ni, Mg)3Si2O5(OH)4)
Limonite (Fe,Ni)O(OH)
Pentlandite
((Ni, Fe)9S8)

GROUP VIII – PHYSICAL PROPERTIES
Iron
White, lustrous
metal
Magnetic
Conductorial
Refractory
Cobalt
Silver-grey
Magnetic
Brittle, hard
Nickel
White, slightly
gold
Hard and ductile
Magnetic

GROUP VIII – CHEMICAL PROPERTIES
Iron:
• Reaction with air to form
various oxide and hydroxide
compounds.
• Fe is pyrophoric in air, but the
bulk metal is oxidized only
when heated.
• Iron reacts on mild heating with a
variety of other non – metals
(halogens, S, P, B, C, Si)
2Fe + 3X2 → 2FeX3 (X = F, Cl, Br)
Fe + 2S → FeS2 (Fool’s gold)

Iron:
• Ferrous halides react with binary halogen acid:
Fe + 2 HX → FeX2 + H2
• Reaction with acids:
2Fe + 6H2SO4conc → Fe2(SO4)3 + 3SO2 + 6H2O
• Fe also takes part in replacing reactions.
Fe + 2AgNO3 deficiency → Fe(NO3)2 + 2Ag
• At high temperature, Fe reduces steam:
3Fe + 4H2O → Fe3O4 + 4H2 (<570oC)
Fe + H2O → FeO + H2 (>570oC)

Iron VI, V and VI:
• The highest oxidation states of iron are found in
compounds of [FeO4 ]2- , [FeO4]3- , [FeO4]4- and [FeO3]2-
• Ferrate(VI) is a powerful oxidant.
[FeO4]2- + 8H+ + 3e- → Fe3+ + 4H2O
• The reaction of K2FeO4 with KOH in O2 at 1000 K gives
K3FeO4, a rare example of an Fe(V) salt.
• Iron(IV) ferrates include Na4FeO4 (made from Na2O2 and
FeSO4), Sr2FeO4 (prepared by heating Fe2O3 and SrO in
the presence of O2) and Ba2FeO4 (made from BaO2 and
FeSO4).

Iron III
• Name is ferric
• Iron (III) halides are made by heating iron with halogens.
• Iron (III) oxide is insoluble in water, but dissolves in acid.
• Iron (III) salts and oxide creates Fe2O3.H2O (also written as
Fe(O)OH) but often mistaken as Fe(OH)3.
FeCl3 + 3NaOH → Fe(OH)3 + 3NaCl
Iron II
• Common name is ferrous.
• Iron (II) halides are made by dissolving the metal in binary
halogenic acid. Fe + 2HX → FeX2 + H2

Cobalt:
• Reaction with air:
3Co(s) + 4O2(g) → 2Co3O4(s)
2Co(s) + O2(g) → 2CoO(s)
• With oxygen with steam as a catalyst:
2Co(s) + O2(g) → 2CoO(s)
• With halogens:
Co(s) + Br2(l) → CoBr2(s) [green]
• With acids:
Co(s) + H2SO4(aq) → Co2+(aq) + SO4
2-(aq) + H2(g)

Cobalt compounds:
• With aqua and halogen ligands:
[Co(H2O)6]2+ + 2NH3→[Co(H2O)4(OH)2] (pink) +2NH4
+
[Co(H2O)6]2+ + 6NH3→[Co(NH3)6]2+ (brown) + 6H2O
[Co(H2O)6]2+ (pink) + 4Cl− ⇌ [CoCl4]2− (blue) + 6H2O
• With halides:
- Anhydrous cobalt dichloride is blue, but the hydrate
form is red.

Nickel:
• With acids:
Ni + HCl → NiCl2 + H2
Nickel is passive in concentrated HNO3
• Nickel doesn’t react with aqueous alkalis.
• With air: they react with each other in high temperatur
Ni + H2O → H2 + NiO
• With halogens: Nickel forms Ni(II) halides with halogen
But with F2, the halide layer prevent further attack.

Nickel compounds:
• Organometallic species: usually in low oxidation states
Nickel is passive in concentrated HNO3
• Ni(II) compounds are important species:
[Ni(NH3)6]2+ [Ni(en)]2+ [NiCl4]2− [Ni(H2O)6]2+
Green Ni(OH)2 is used in NiCd batteries
• Ni(IV) compounds are formed under influence of
really strong oxidants. Ex: KNiO6 is formed under oxidation
of [Ni(H2O)6]2+ by [S2O8]2- with [IO4]-
• Ni(I) is uncommon: ex [Ni2(CN)6]4-

Iron:
• Making steel.
• Hemoglobin in blood and myoglobin in
muscle
• Essential for energy production
(respiratory chain)
• DNA Replication
• Glucose Metabolism
• Enzyme systems
GROUP VIII – APPLICATIONS

Cobalt:
• Making magnets and batteries
• Other alloys of cobalt are used in jet
turbines and gas turbine generators
• Used in electroplating
• Cobalt salts produce brilliant blue colours
for many uses.
Roles (in Biology)
• Trace element Part of the active site of
vitamin B12
• Cancer treatment and preserve food
(Radioactive 60Co)
• Correct mineral deficiencies (animals)

Nickel:
• It is used in coinage, plating, alloys.
• A trace mineral in human and animal body.
• Low nickel: reduced growth, decreased life
expectancy, reduced iron absorption leads to
anaemia.
• Low nickel in human body can interrupt
absorption of calcium into the skeleton.
• Key component in hydrogenase biosynthetic
processes.
• Nickel is found in urease – an enzyme that
assist plant hydrolyse urea.

GROUP VIIIB – NATURAL RESOURCES
IRON:
 Iron is the second cheapest most abundant metal
 Nearly 5.6% of Earth’s crust.
 Major iron ores are hematite, Fe2O3, magnetite,
Fe3O4, limonite, FeO(OH), and siderite, FeCO3.
 Pure iron is almost never found in nature.

GROUP VIIIB – NATURAL RESOURCES
RUTHENIUM:
 Ru is found in nature with the other platinum group.
Commercially, it is obtained from pentlandite (a
sulfide of iron and nickel) with contains small
quantities of ruthenium.
OSMIUM:
 Osmium occurs uncombined in nature and also in
the mineral osmiridium (an alloy with iridium).
Most osmium is obtained commercially from the
wastes of nickel refining.

GROUP VIIIB – CHEMICAL PROPERTIES
RUTHENIUM & OSMIUM
 React with O2:
Ru + O2  (>870) RuO2 (non-volatile)
Os+ O2  (>870) OsO4 (volatile)
 Reacte with F2 and Cl2 when heated.
 Attacked by mixtures of HCl and oxidizing agents,
and by molten alkalis.
 Metals:

RUTHENIUM & OSMIUM
 Ruthenium(VIII) oxide RuO4 and Osmium(VIII)
oxide OsO4 is unstable and also a very powerful
oxidant.
 All the binary halides RuX3 are known but for Os,
only OsCl3 and OsI3 have been established; OsF4 is
the lowest fluoride of Os.
 Binary halides of Ru(II) and Os(II) are not well
characterized and there are no oxides
 Compounds:

RUTHENIUM & OSMIUM
 Most of the chemistry of Ru(II) and Os(II) concerns
complexes: diamagnetic, low-spin d6, octahedral.
 Many low oxidation state complexes of Ru and Os
including those of Ru(II) and Os(II) are stabilized by
PR3 (π-acceptor) ligands.
 Complexes:

GROUP VIIIB – BIOLOGICAL ROLE
IRON:
In biological systems, these oxidation states are limited
primarily to the ferrous (+2), ferric (+3) and ferryl (+4)
states.
 Iron required for Hemoglobin in blood
 Needed for Myoglobin in muscle
 Essential for energy production (respiratory chain)
 DNA Replication
 Glucose Metabolism
 Enzyme systems in the body that use iron include
Mono - and Di – Oxygenases, protective Peroxidases
like catalase and Myeloperoxidase and Several
Oxidoreductases.
Foods contain Fe:

RUTHENIUM:
 Ruthenium has no known biological role.
Ruthenium(IV) oxide is highly toxic.
OSMIUM:
 Osmium has no known biological role. The metal is
not toxic, but its oxide is volatile and very toxic,
causing lung, skin and eye damage.

GROUP VIIIB – APPLICATION
IRON:
In industry:
- Be used to make steel.
- Be the manufacture of tools and weapons.
In medicine: Iron is usually administered orally to a
patient as iron supplement tablets containing an Fe(II)
or Fe(III) salt. Iron(II) salts are more typical because
they exhibit better solubilities than Fe(III) salts at
physiological pH, but Fe(III) has the advantage that,
unlike Fe(II), it is not susceptible to oxidation in
aqueous solution.

RUTHENIUM:
 Used in electronics industry for chip resistors and
electrical contacts.
 Used for catalysts for ammonia and acetic acid
production.
 Used in solar cells, which turn light energy into
electrical energy.
 Used in some jewellery as an alloy with platinum.
OSMIUM:
 Used to produce very hard alloys for fountain pen
tips, instrument pivots, needles and electrical
contacts
 Used in the chemical industry as a catalyst.

PALADIUM & PLATINUM
 Metals:
 Resistant to corrosion.
 Pt is more inactive than Pd.
 Pd reacts with O2, F2 and Cl2 at high temperature.
 Both can be attacked by aqua regia and molten alkali
metal oxide.
 Pt + 2 HNO3+ 6 HCl + Cl2 → + 3 H2O + 1/2 O2 +
H2PtCl6 (chloroplatinic acid) + 2 NOCl
 M(II) and M(IV) are two common oxidation state.

PALADIUM & PLATINUM
 Compounds – M(IV) compounds:
 All the M(IV) halides are known
 M + 2X2  MX4
 M(IV) is stable for Pt than Pd.
 Chloroplatinic acid is a great starting material

PALADIUM & PLATINUM
 Compounds – M(II) compounds:
 Halides of Pd(II) and Pt(II) except PtF2 are known.
 M(Cl)2 is the precursor for preparation of other
compounds.
 MCl2 + F2 -> MF¬4
 Cisplatin is an anticancer chemical

PALADIUM & PLATINUM
 Compounds:
 +4 and +5 are the highest oxidation numbers for the
two metals.
 MBr3 and other M(III) species are mixed-valence
compounds.

NICKEL:
 A trace mineral.
(Low nickel: reduced growth, decreased life expectancy,
reduced iron absorption leads to anaemia. Low nickel in
human body can interrupt absorption of calcium into the
skeleton.)
 Key component in hydrogenase biosynthetic
processes.
 Nickel is found in urease – an enzyme that assist
plant hydrolyse urea.

PALADIUM:
 Toxic???
PLATINUM:
 Beside Cisplatin and Carboplatin, Oxaliplatin is also
used in chemotherapy.
 Platinum salts can be carcinogens, or cause allergy,
deafness, stimulation to dangerous chemicals in
human body, such as selenium.

NICKEL:
 Used to plate other metals to protect them.
 Used in making alloys such as stainless steel
 Used in toasters and electric ovens.
 Nickel is used in batteries.
 Used as a catalyst for hydrogenating vegetable oils.
Adding nickel to glass gives it a green colour.

PALADIUM:
PLATINUM:

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