Transition Metals: Properties and Applications

• Transition metals possess societal utility: iron makes steel, copper makes electrical wiring and water pipes, titanium makes paint, and silver makes photographic paper.
• Manganese, chromium, vanadium, and cobalt serve as steel additives.
• Platinum is useful for industrial and automotive catalysts.
• The United States imports over 60 "strategic and critical" minerals, such as cobalt, manganese, platinum, palladium, and chromium.
• Around 90% of the required amounts of these metals is imported, this highlights their importance to the U.S. economy and defense.
• Transition metal ions play pivotal biological roles, including oxygen transport and storage via iron complexes.
• Molybdenum and iron compounds catalyze nitrogen fixation.
• Zinc is present in >150 human biomolecules.
• Copper and iron are essential in the respiratory cycle.
• Cobalt is in essential biomolecules like vitamin B12.

Transition Metals: A Survey - General Properties

• Unlike representative elements with vertical group similarities, transition metals share similarities within periods and vertical groups.
• The last electrons supplement transition metals as inner electrons: d electrons (d-block) and f electrons (lanthanides/actinides).
• Inner d and f electrons do not readily participate in bonding like valence s and p electrons.
• Chemistry of transition elements isn't significantly affected by the gradual increase in electrons like it is with representative elements.
• Group designations on the periodic table do not directly relate to chemical behavior like A groups do for representative elements, so these designations aren't used.

The Lanthanides: Critical Elements

• Rare earth" is a misnomer for lanthanides, with many being abundant and crucial for modern life.
• Hybrid cars contain ~10 kg of lanthanum (Ni-metal hydride batteries) and smaller amounts of other lanthanides (electric motors & generators).
• Windmills depend on ~1-ton magnets that have 100s of pounds of neodymium (Nd2Fe14B).
• Neodymium-iron-boron magnets appear in computer disk drives.
• Lanthanides play a key role in global economics, as the elements are important to modern technology..
• Although China has ~52% of the world’s rare-earth reserves, in 2010 it produced almost 100% of rare-earth metals and more than 94% of rare-earth oxides.
• China produces rare earths at a much lower cost compared to other countries.
• The United States holds about 13% of the world’s supply of rare earths, production is minimal in comparison.
• A Molycorp plant in Mountain Pass, California, shut in 2002 because it couldn't compete with China's prices.
• The Molycorp plant made ore with 49% cerium, 33% lanthanum, 13% praseodymium, 4% samarium, and 1% heavier rare-earth elements.
• China has lowered rare-earth exports, which caused concerns about supplies for other nations like the U.S.
• As a result, Molycorp reopened in 2010.
• Rare-earth elements will become critical to the global economy and world politics in the coming years.
• Transition metals are typical metals; exhibit metallic luster and high electrical and thermal conductivities.
• Silver is the best conductor of heat and current, but copper is a close second. This explains copper's prevalence in home and factory electrical systems.
• Transition metal properties significantly vary.
• Tungsten has a very high melting point of 3400°C.

Transition Metal Characteristics

• The metals exhibit more than one oxidation state
• The cations in them are often complex ions.
• Complex ions are metal ions surrounded by a number of ligands (Lewis bases)
• Compound [Co(NH3)6]Cl3 contains Co(NH3)63+ cations and Cl- anions.

First-Row Transition Metals

• The 3d orbitals initiate filling after 4s orbital completion (after calcium, [Ar]4s²).
• Scandium has one 3d electron, titanium has two, vanadium has three.
• Chromium’s electron configuration is [Ar]4s¹3d5, not the expected [Ar]4s²3d4.
• Tungsten, in the same vertical group as chromium, has the configuration [Xe]6s24f145d4 unlike the expected configuration, therefore half-filled shells are not universally found.
• Rigorous assessment of chromium's electron configuration involves electron interactions.
• Orbital energies vary within an atom based on other occupied orbitals.
• 4s²3dⁿ and 4s¹3dⁿ⁺¹ configurations possess similar energies; 4s²3dⁿ is lower in energy except for chromium and copper.
• The 3d orbitals’ energy in transition metal ions is significantly less than that of the 4s orbital.
• The remaining electrons occupy the 3d orbitals, meaning First-row transition metal ions do not have 4s electrons.
• Manganese [Ar]4s²3d⁵ has a Mn²⁺ configuration of [Ar]3d⁵.
• Neutral titanium has the [Ar]4s²3d² configuration, but Ti³⁺ has [Ar]3d¹.
• Transition metals can form a variety of ions by losing one or more electrons.
• The first five transition metals’ maximum oxidation state corresponds to the loss of all the 4s and 3d electrons.
• For example, chromium ([Ar]4s¹3d⁵) maximum oxidation state is +6.
• Metals towards the period's right end do not exhibit the maximum oxidation states; however, 2+ ions are the most common.
• The higher oxidation states of the metals are not seen because the energy of the 3d orbitals becomes lower as the nuclear charge increases, making the easier to remove.
• Ionization energy increases gradually across the period.
• The third ionization energy increases faster than the first ionization energy, clear evidence of the significant decrease in the energy of the 3d orbitals.
• As the reducing abilities of the first-row transition metals go from left to right across the period they generally decrease. Only chromium and zinc do not follow this trend.
• In comparing the 3d, 4d, and 5d transition series, there's a general, not regular, decrease in size going from left to right across each series.
• The radius increases significantly as you transition from 3d to 4d metals.
• The radius of 4d and 5d metals display remarkable similarity.
• The lanthanide contraction leads to the similarity of the 4d and 5d metals.
• The lanthanide series involves filling the 4f orbitals, they do not add to the atomic size because they are buried in the interior of their atoms.
• The increasing nuclear charge offsets the normal increase in size due to changing from one primary quantum level to the next causing the radii of lanthanide elements to decrease.
• 5d elements are nearly identical in size to 4d elements.
• Hafnium and zirconium have remarkably similar chemical properties.
• Separating hafnium and zirconium often requires fractional distillation of their compounds because they always occur together in nature and its most difficult to separate.
• Differences between 4d and 5d elements in a group gradually increase.
• Niobium and tantalum are quite similar, but less so than zirconium and hafnium.
• Although generally less well known than the 3d elements, the 4d and 5d transition metals have certain very useful properties.
• Zirconium and zirconium oxide (ZrO2) resist to high temperatures and are used, along with niobium and molybdenum alloys, for space vehicle parts exposed to high temperatures during reentry.
• Niobium and molybdenum are important alloying materials for some types of steel.
• Tantalum is often used for surgical clips as it is resistant to attack by body fluids.
• The platinum group metals—ruthenium, osmium, rhodium, iridium, palladium, and platinum—are all quite similar and are widely used as catalysts for many industries.

Specific Properties of 3d Transition Metals

• Scandium exists in +3 oxidation state compounds like ScCl3, Sc2O3, and Sc2(SO4)3.
• Scandium's chemistry resembles that of the lanthanides, with colorless and diamagnetic compounds due to Sc³⁺’s lack of d electrons.
• Scandium metal, is made by electrolysis of molten ScCl3, is not widely used because of its scarcity. However, it appears in some electronics, such as high-intensity lamps.
• Titanium is 0.6% of the earth's crust by mass.
• Titanium is ideal as structural material because of its low density and high strength, particularly in jet engines.
• Boeing 747 jetliner engines use ~5000 kg of titanium alloys.
• Titanium has resistance to chemical attack and is a useful material for making pipes, pumps and reaction vessels in the chemical industry.
• Titanium dioxide is used as the white pigment in items like paper, paint, linoleum, plastics, synthetic fibers, whitewall tires and sunscreens.
• Approximately 700,000 tons of TiO2 are used yearly in those and same products.
• Titanium dioxide is commonly found but the main ores are rutile (impure TiO2) and ilmenite (FeTiO3).
• Rutile is processed with chlorine to produce volatile TiCl4, which is then separated from any impurities before being burned to form TiO2.
• Ilmenite is treated with sulfuric acid to form a soluble sulfate mixture.
• This aqueous mixture is then allowed to stand under a vacuum.
• Solid FeSO4·7H2O is formed and removed.
• The remaining mixture is heated up, and the insoluble titanium(IV) oxide hydrate (TiO2·H2O) forms.
• Hydration water is eliminated by heating to create pure TiO2.
• In its compounds titanium commonly exists in the +4 oxidation state
• TiO2 and TiCl4 are examples; the latter is a colorless liquid (bp = 137°C) that fumes in moist air to produce TiO2.
• Titanium(III) compounds may be produced through the reduction of compounds with titanium in the +4 state.
• In aqueous solution Ti³⁺ exists as the purple Ti(H2O)6³⁺ ion, which is slowly oxidized to titanium(IV) by air.
• Titanium(II) lacks stability in aqueous solutions but exists in solid-state compounds like TiO and dihalides like TiX2.
• Vanadium is widely available throughout the earth's crust for 0.02% by mass. It is mostly used in alloys with other metals like iron (80% of vanadium is used in steel) and titanium.
• Vanadium(V) oxide (V2O5) serves as the industrial catalyst in producing materials like sulfuric acid.
• Steel gray Vanadium can be made from the reduction of fused salts like VCl2 through the use of metal that is steel gray and is both hard and corrosion-resistant.
• The most significant oxidation state for vanadium is +5 in compounds like the orange V2O5 (mp = 650°C) and colorless VF5 (mp = 19.5°C)
• Oxidation states ranging from +5 to +2 are available in aqueous solutions
• Higher oxidation states, +5 and +4, do not exist as hydrated ions of the type Vn+(aq).
• Those highly charged ions cause the water molecules attached to be very acidic
• With these +5 and +4 oxidation states the H+ ions are gone to provide oxycations VO2+ and VO2+.
• Hydrated V³+ and V2+ ions can easily be oxidized and are able to work in a reducing agents in aqueous solution.
• Although chromium is relatively rare, it is a very significant industrial material.
• Chromite is the primary ore of chromium (FeCr2O4), can be diminished through carbon to yield ferrochrome.
• which can be put straight into iron for steelmaking.
• Chromium metal offers exceptional protection at high temperatures and is typically used to plate steel.

Chromium Compounds

• Commonly forms compounds in which it has an oxidation state of +2, +3, or +6
• Cr²+ (chromous) ion acts a powerful reducing agent in aqueous solution.
• O2 traces may also be eliminated from these from gases via bubbling the gaseous mixture Through a Cr²+ solution.
• Chromium(VI) species are good at working as oxidizing agents; particularly in acidic solution. Chromium(VI) acts as as dichromate Cr2O72¯, is lowered in to Cr3+ ion.
• Dichromate is able to be an oxidizing agent that will be pH dependently; in this instance [H+] will increase this is per Le Châtelier's principle. Chromate ion exists in basic solution.
• Red chromium(VI) oxide (CrO3) is able to be dissolved in water and produce a good acidic, red-orange solution.
• It is plausible in order to precipitate bright orange dichromate salts, just like K2Cr2O7, from these solutions
• As the solutions become more basica, the solution transforms to bright yellow and offers chro- mate salts and makes Na2CrO4 readily obtained. A mixture including chromium(VI) oxide as well as concentrated sulfuric acid, mostly cited As cleaning solution

Manganese

• Manganese is quite readily available with 0.1% of earth's crust; yet US sources do not have any of this.
• Manganese the compound is most often used in the production of especially hard steel and is best used for banks bank vaults, as well as armor plate
• Most manganese is in the production of especially hard steel and is best used for bank vaults, as well as armor plates
• All of manganese, can exist in all oxidation states, including one that is +2 and one with +7; despite this you'll find +2 and +7 to be most common. Manganese(II) forms an extended number of salts.
• Mn2+ is present and forms Mn(H2O)62+ in Aqueous solution and has a pink tone
• In another aspect manganate(VII) is available in the intensely purple permanganate ion and provides MnO4-. MnO4 the molecule serves a purpose a primary analytic reagent available within acidic solution, the MnO4- ion behaves similarly and functions as an impactful oxidizing force, and does so by reducing Mn2+.

Iron

• White and glistening Iron, along with its relatively high electrical and thermal conductivities, is quite corrosion-resistant.

Copper

• Copper is often more widely allocated by nature in the types of ores that provide sulfides chloride as well as carbonates values as copper. it offers an Electrical conductivity it maintains a High Resistance from corrosion.
• Its utilization is commonplace for plumbing including that of 50% this is a production copper for electrical purposes

Coordination Compounds:

• Composed of a metallic central ion or atom (typically from d-block elements) that is bonded/ attached one or multiple ligands (atoms, ions, or molecules having a lone pair of electrons)
• The metallic center ion / atom performs as central ion a Lewis acid (electron-pair acceptor); ligands a Lewis base (electron-pair donator) due lone electron-pair availability to donate to the metallic center, forming a metal-ligand or coordinate covalent bond.
• The arrangement of ligands is called coordination sphere.
• Counter ions are ions/molecules are available for balancing coordination sphere's charge.
• Metallic center of atoms is assigned oxidation numbers oxidation state, this is the net electrical charge the metal possesses.
• Oxidation numbers will be derived, and we must know every ligand molecule's / ion's charge. Neutral ligand has value of zero
• All transition metal ions form coordination compounds, that is often colored and paramagnetic, a property that relates to coordination's specific electronic structure.
• The number ligands that are attached a metallic central is referred as The coordination number; usually, coordination numbers range 2-8 which corresponds for geometry linear in the 2 and higher towards octahedral

Coordination Complex Rules

• Naming coordination complexes rules:
  • Cation comes first, and that of anion after.
  • Ligands will be cited just before metallic ion.
• anionic ligands
  • Adding "o" suffix into root and name as anionic For instance, halides such fluoro and chloro; hydroxide as hydroxo and that of cyanide is cyano.
• neutral ligands
  • neutral ligands maintains its name with exceptions, H2O named aqua, NH3, CO carbonyl and NO, which is nitrosyl, so those 4 neutral ligands is always an exception
  • Use the prefixes below towards listing number simple ligands. mono-, di-, tri-, tetra-, penta-, and hexa- are employed indicate amount simple ligands.
  • Complicated will need for the prefixes, bis, tris-, tetrakis etc, esp when exists a di,, tri already. For instance, bis(ethylenediamine)dichloroiron(II)
• metallic center's Assign Oxidation state with Roman number.
• Ligands are ordered alphabetically.
• -ate suffix if complex is negatively-charged.
• Ligands and Metals are identified and listed along with rules

Isomerism-Structural/Stereo

• Isomers share chemical composition(same formulas); They will demonstrate properties but demonstrate diverse atomic arrangement. We may separate the class Isomers as "Structural Isomers and Stereo-" which those subclasses with it.
• structural with coordinate / the linker
• Stereo features geometric / the light aspect.

Crystal Field Model

• Accounts for magnetic properties and color in complex ions.
• Approximates ligands as negative point charges.
• Assumes metal-ligand bonding has been entirely ionic
• Illustrates fundamental principles through application of the octahedral complex.
• Two orbitals to observe the charge of eg2 and dx2-y2. where its direct to charge.
• Other one the set of orbitals. dxy dxz and dy where this lobes is between. - Point-charge ligands do improve any and the whole d orbitals
• The D will be split to the ligands it changes by this means that is required by the photons. Several octahedral complexes in table where 19.17 is listed at table..
• Some geometry will also be related towards considering such complexes The tetrahedral arranges in each 3D metal

Crystal Model III

• The crystal field model helps planar/linear
• Square geometry 2D in picture

Molecular Orbital Model

• Realistically views metal-Ligand Bonds -MO . There was one exception to that: MO had limited views in light of the bonding to 806