Doc Brown's Chemistry  Advanced Level Inorganic Chemistry Periodic Table Revision Notes – Transition Metals

Part 10. Transition Metals 3d–block:  

10.4 Titanium Chemistry

Titanium exhibits oxidation states of +2, +3 and +4. There are many titanium(III) complex ions and titanium is most widely known for its strong light alloys and the white pigment titanium(IV) dioxide TiO2.

principal oxidation states of titanium, redox reactions of titanium, ligand substitution displacement reactions of titanium, balanced equations of titanium chemistry, formula of titanium complex ions, shapes colours of titanium complexes, formula of compounds

(c) doc b GCSE/IGCSE Periodic Table Revision Notes * (c) doc b GCSE/IGCSE Transition Metals Revision Notes

INORGANIC Part 10 3d block TRANSITION METALS sub–index: 10.1–10.2 Introduction 3d–block Transition Metals * 10.3 Scandium * 10.4 Titanium * 10.5 Vanadium * 10.6 Chromium * 10.7 Manganese * 10.8 Iron * 10.9  Cobalt * 10.10 Nickel * 10.11 Copper * 10.12 Zinc * 10.13 Other Transition Metals e.g. Ag and Pt * Appendix 1. Hydrated salts, acidity of hexa–aqua ions * Appendix 2. Complexes & ligands * Appendix 3. Complexes and isomerism * Appendix 4. Electron configuration & colour theory * Appendix 5. Redox equations, feasibility, Eø * Appendix 6. Catalysis * Appendix 7. Redox equations * Appendix 8. Stability Constants and entropy changes * Appendix 9. Colorimetric analysis and complex ion formula * Appendix 10 3d block – extended data * Appendix 11 Some 3d–block compounds, complexes, oxidation states & electrode potentials * Appendix 12 Hydroxide complex precipitate 'pictures', formulae and equations

Advanced Level Inorganic Chemistry Periodic Table Index * Part 1 Periodic Table history * Part 2 Electron configurations, spectroscopy, hydrogen spectrum, ionisation energies * Part 3 Period 1 survey H to He * Part 4 Period 2 survey Li to Ne * Part 5 Period 3 survey Na to Ar * Part 6 Period 4 survey K to Kr and important trends down a group * Part 7 s–block Groups 1/2 Alkali Metals/Alkaline Earth Metals * Part 8  p–block Groups 3/13 to 0/18 * Part 9 Group 7/17 The Halogens * Part 10 3d block elements & Transition Metal Series * Part 11 Group & Series data & periodicity plots * All 11 Parts have their own sub–indexes near the top of the pages


10.4. Chemistry of Titanium Ti, Z=22, 1s22s22p63s23p63d24s2 

data comparison of titanium with the other members of the 3d–block and transition metals

Z and symbol 21 Sc 22 Ti 23 V 24 Cr 25 Mn 26 Fe 27 Co 28 Ni 29 Cu 30 Zn
property\name scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc
melting point/oC 1541 1668 1910 1857 1246 1538 1495 1455 1083 420
density/gcm–3 2.99 4.54 6.11 7.19 7.33 7.87 8.90 8.90 8.92 7.13
atomic radius/pm 161 145 132 125 124 124 125 125 128 133
M2+ ionic radius/pm na 90 88 84 80 76 74 72 69 74
M3+ ionic radius/pm 81 76 74 69 66 64 63 62 na na
common oxidation states +3 only +2,3,4 +2,3,4,5 +2,3,6 +2,3,4,6,7 +2,3,6 +2,3 +2,+3 +1,2 +2 only
outer electron config.[Ar]... 3d14s2 3d24s2 3d34s2 3d54s1 3d54s2 3d64s2 3d74s2 3d84s2 3d104s1 3d104s2
Elect. pot. M(s)/M2+(aq) na –1.63V –1.18V –0.90V –1.18V –0.44V –0.28V –0.26V +0.34V –0.76V
Elect. pot. M(s)/M3+(aq) –2.03V –1.21V –0.85V –0.74V –0.28V –0.04V +0.40 na na na
Elect. pot. M2+(aq)/M3+(aq) na –0.37V –0.26V –0.42V +1.52V +0.77V +1.87V na na na

Elect. pot. = standard electrode potential data for titanium (EØ at 298K/25oC, 101kPa/1 atm.)

na = data not applicable to titanium

Extended data table for TITANIUM

property of titanium/unit value for Ti
Ti melting point/oC 1668
Ti boiling point/oC 3287
density of Ti/gcm–3 4.54
1st Ionisation Energy/kJmol–1 658
2nd IE/kJmol–1 1310
3rd IE/kJmol–1 2652
4th IE/kJmol–1 4175
5th IE/kJmol–1 9573
atomic radius Ti/pm 145
Ti2+ ionic radius/pm 90
Relative polarising power Ti2+ ion 2.2
Ti3+ ionic radius/pm 76
Relative polarising power Ti3+ ion 3.9
Ti4+ ionic radius/pm 68
Polarising power Ti4+ ion 5.9
oxidation states of Ti, less common/stable +2, +3, +4
simple electron configuration of Ti 2,8,10,2
outer electrons of Ti [Ar]3d24s2
Electrode potential Ti(s)/Ti2+(aq) –1.63V
Electrode potential Ti(s)/Ti3+(aq) –1.21V
Electrode potential Ti2+(aq)/M3+(aq) –0.37V
Electronegativity of Ti 1.54

Advanced Inorganic Chemistry Page Index and Links

  • Extraction of titanium

    • Titanium ore is mainly the oxide TiO2, which is converted into the tetrahedral shaped covalent liquid titanium tetrachloride TiCl4 by heating with carbon and chlorine. There is no change in oxidation state of titanium in this reaction (+4 in both compounds involved)

    • The chloride is then reacted with sodium or magnesium to form titanium metal and sodium chloride or magnesium Chloride.

    • This reaction is carried out in an atmosphere of inert argon gas so non of the metals involved becomes oxidised by atmospheric oxygen.

    • TiCl4 + 2Mg ==> Ti + 2MgCl2 or TiCl4 + 4Na ==> Ti + 4NaCl

    • Overall the titanium oxide ore is reduced to titanium metal (overall O loss, oxide => metal) and the magnesium or sodium acts as a reducing agent.

  • Uses of TITANIUM

    • Titanium is a hard silvery–white lustrous metal of relatively low density.

    • Titanium is relatively resistant to corrosion and is a very important metal for various specialised uses.

    • Titanium carbide, TiC, is used in making extremely hard alloys for high speed tools e.g. the drill bit.

    • Titanium alloys are amongst the strongest and lightest of metal alloys.

    • It is used in aeroplanes, in nuclear reactor alloys, chemical reactor vessels and for replacement hip joints.

    • With a lighter density of 4.4 g/cm3 compared to steel (~7.9 g/cm3) its just as strong as steel and with the added advantage of being unreactive towards oxygen and water at room temperature so does not suffer the rusting of iron corrosion.

    • Titanium(IV) oxide, TiO2, is an important white pigment used in the paints industry.

      • Note that Ti4+ has a [Ar]3d0 structure, hence, with no 3d electrons it is colourless (see colour theory).

    • Titanium(IV) oxide is also used in paper making, ceramics and textile industries.

    • Titanium(IV) chloride and other covalent titanium compounds are used as polymerisation catalysts (e.g. Ziegler–Natta catalysts) for manufacturing polyalkenes like poly(propene).


The Chemistry of TITANIUM

  • Titanium extraction and Ti(IV) CHEMISTRY

  • It is more difficult  to extract from its ore than other more common metals so is not cheap!

    • Titanium is extracted from the raw material rutile ore which contains titanium dioxide. This is a high melting ionic compound Ti4+(O2–)2.

    • Carbon reduction of the oxide to the metal is not that practical due to titanium carbide formation so the titanium(IV) oxide is initially converted to titanium(IV) chloride which is then reduced to the metal with a more reactive metal in a displacement reaction.

      • Tungsten (W), another transition metal, cannot be obtained from reduction of its oxide for the same reason.

    • The rutile titanium oxide ore is heated with carbon and chlorine to make titanium(IV) chloride

      • TiO2 + 2Cl2 + C ==> TiCl4 + CO2

    • After the oxide is converted into TiCl4 which is then reacted with sodium or magnesium to form titanium metal and sodium chloride or magnesium Chloride. The sodium and magnesium act as the reducing agent in this batch process.

      • This reaction is carried out in an atmosphere of inert argon gas so non of the metals involved becomes oxidised by atmospheric oxygen.

        • Advanced Inorganic Chemistry Page Index and LinksTiCl4 + 2Mg ==> Ti + 2MgCl2  or  TiCl4 + 4Na ==> Ti + 4NaCl

      • These are examples of metal displacement reactions e.g. the less reactive titanium is displaced by the more reactive sodium or magnesium.

      • Overall the titanium oxide ore is reduced to titanium metal (overall O loss from ox. state +4, oxide => metal with ox. state 0)

      • TiCl4 is covalent liquid which (i) hydrolyses back to the oxide in water , BUT (ii) dissolves in conc. hydrochloric acid to form the hexachlorotitanate(IV) complex ion.

        • (i) TiCl4(l) + 2H2O(l) ==> TiO2(s) + 4HCl(aq/g) (fumes in air!)

        • (ii) TiCl4(l) + 2Cl(aq) ==> [TiCl6)]2–(aq) (typical complex anion)

Pd s block d blocks and f blocks of metallic elements p block elements
Gp1 Gp2 Gp3/13 Gp4/14 Gp5/15 Gp6/16 Gp7/17 Gp0/18
1

1H

2He
2 3Li 4Be The modern Periodic Table of Elements

ZSymbol, z = atomic or proton number

3d block of metallic elements: Scandium to Zinc

5B 6C 7N 8O 9F 10Ne
3 11Na 12Mg 13Al 14Si 15P 16S 17Cl 18Ar
4 19K 20Ca 21Sc

[Ar]3d14s2

scandium

22Ti

[Ar]3d24s2

titanium

23V

 [Ar] 3d34s2

vanadium

24Cr

[Ar] 3d54s1

chromium

25Mn

   [Ar]   3d54s2

manganese

26Fe

[Ar] 3d64s2

iron

27Co

[Ar] 3d74s2

cobalt

28Ni

[Ar] 3d84s2

nickel

29Cu

[Ar] 3d104s1

copper

30Zn

[Ar] 3d104s2

zinc

31Ga 32Ge 33As 34Se 35Br 36Kr
5 37Rb 38Sr 39Y 40Zr 41Nb 42Mo 43Tc 44Ru 45Rh 46Pd 47Ag 48Cd 49In 50Sn 51Sb 52Te 53I 54Xe
6 55Cs 56Ba 57-71 72Hf 73Ta 74W 75Re 76Os 77Ir 78Pt 79Au 80Hg 81Tl 82Pb 83Bi 84Po 85At 86Rn
7 87Fr 88Ra 89-103 104Rf 105Db 106Sg 107Bh 108Hs 109Mt 110Ds 111Rg 112Cn 113Uut 114Fl 115Uup 116Lv 117Uus 118Uuo
  *********** *********** ************ ************ ************** ********** ********** ********** ********** **********  

  • When titanium(IV) compounds are dissolved in water of acid the oxo–cation [TiO]2+ is formed.

  • The electrode potential chart highlights the values for various oxidation states of titanium.

  • TITANIUM(III) CHEMISTRY

  • Titanium(III) compounds can be obtained from Ti(IV) salts by using a zinc/dil. sulphuric acid reduction agent.

    • eg the colourless oxotitanium(IV) ion is reduced to the purple hexaaquatitanium(III) ion

    • colourless Ti(IV) as [TiO]2+ ==> Ti(III) in acid solution giving the purple [Ti(H2O)6)]3+(aq).

    • but it is readily oxidised back to Ti(IV) by dissolved oxygen from the atmosphere (see electrode potential chart TiO2+/Ti3+ +0.10V is less positive than O2+H+/H2O +1.23V in acid solution).

    • Titanium(III) chloride TiCl3 is a violet solid.

  • TITANIUM(II) CHEMISTRY

  • Titanium(II) chloride TiCl2 is a black solid.

  • The violet hexaaquatitanium(II) ion [Ti(H2O)6)]2+ ion can be formed by reducing Ti(IV) or Ti(III) with a metal/acid mixture but it is very unstable in redox terms, ie readily oxidised by dissolved oxygen from the atmosphere.

  • Ti2+, a powerful reducing agent, will reduce water to hydrogen (i.e. oxidised by water to Ti3+) and because it is rapidly oxidised by air it cannot exist in aqueous solution.

    • From the electrode potential chart you can see that the electrode potential of Ti3+/Ti2+ is –0.37V and is less positive than electrode potential O2/H+/H2O +1.23V in acid solution.

  • Comparison of titanium with a typical Group 4 metal e.g. tin

    • Tin only exhibits oxidation states of +2 and +4, there is no intermediate +3 compounds.

    • Tin compounds are usually colourless.

    • Physically, tin is a much weaker metal with much lower melting/boiling point than titanium.

  • Summary of some complexes–compounds & oxidation states of titanium compared to other 3d–block elements


Appendix: More on how titanium is produced and what is it used for?

Titanium is a very important metal for various specialised uses. It is more difficult  to extract from its ore than other, more common metals.

  • Titanium is a transition metal of low density ('light'), strong and resistant to corrosion.

    • Titanium alloys are amongst the strongest lightest of metal alloys and used in aircraft production.

    • There is a note about the bonding and structure of alloys on another page.

    • As well as its use in aeroplanes it is an important component in nuclear reactor alloys and for replacement hip joints because of its light and strong nature AND it doesn't easily corrode.

      • See more on titanium - gold alloys and use in orthopaedic situations.

    • It is one of the main components of Nitinol 'smart' alloys. Nitinol belongs to a group of shape memory alloys (SMA) which can 'remember their original shape'. For example they can regain there original shape on heating (e.g. used in thermostats in cookers , coffer makers etc.) or after release of a physical stress (e.g. used in 'bendable' eyeglass frames, very handy if you tread on them!). The other main metal used in these very useful intermetallic compounds is nickel.

  • Titanium is extracted from the raw material is the ore rutile which contains titanium dioxide.

  • The rutile titanium oxide ore is heated with carbon and chlorine to make titanium chloride

    • TiO2 + 2Cl2 + C ==> TiCl4 + CO2

  • After the oxide is converted into titanium chloride TiCl4, it is then reacted with sodium or magnesium to form titanium metal and sodium chloride or magnesium Chloride. This is an expensive process because sodium or magnesium are manufactured by the costly process of  electrolysis (electricity is the most costly form of energy).

    • This reaction is carried out in an atmosphere of inert argon gas so none of the metals involved becomes oxidised by atmospheric oxygen.

    • TiCl4 + 2Mg ==> Ti + 2MgCl2 or TiCl4 + 4Na ==> Ti + 4NaCl

    • These are examples of metal displacement reactions e.g. the less reactive titanium is displaced by the more reactive sodium or magnesium.

    • Overall the titanium oxide ore is reduced to titanium metal (overall O loss, oxide => metal)

  • Metals can become weakened when repeatedly stressed and strained. This can lead to faults developing in the metal structure called 'metal fatigue' or 'stress fractures'.

    • If the metal fatigue is significant it can lead to the collapse of a metal structure.

    • So it is important develop alloys which are well designed, well tested and will last the expected lifetime of the structure whether it be part of an aircraft (eg titanium aircraft frame) or a part of a bridge (eg steel suspension cables).

  • There are many applications of titanium alloys in the industrial, automotive and aerospace fields and titanium has been widely used for implant devices that replace patients’ hard tissues eg in orthopaedic surgery techniques. It is accepted that commercially pure Ti is a highly biocompatible material due to the spontaneous build-up of an inert and stable oxide layer [Titanium(IV) oxide, TiO2].

    • Additional properties that make Ti suitable for biomedical applications include high strength-to-weight ratio, relatively low electrical conductivity, low ion-formation levels in aqueous environments (eg soft tissue).

    • Titanium is one of a few materials capable of osseointegration, which means it exhibits mechanical retention of the implant by the host bone tissue, which stabilizes the implant without any soft tissue layers between the two.

    • These properties enable a wide use of titanium for devices such as artificial knee and hip joints, screws and shunts for fracture fixation, bone plates, pacemakers and cardiac valve prosthesis and dental applications of Ti are just as common, including implants and their components such as inlays, crowns, overdentures, and bridges.

    • However, the pure titanium is not strong enough for a number of medical purposes and there is a need for developing more superior Ti-based alloys.

    • Apparently Ti exhibits poor machineability, which reduces tool life, increases the processing time and is problematic when the elimination of a dental Ti prosthesis is necessary. Both the machineability and hardness can be improved by alloying Ti with another element eg gold.

    • A number of toxic effects were reported in permanent implants [using vanadium and aluminium containing titanium alloys was discontinued.

    • Among biocompatible elements, the addition of Ag and Cu nearly doubles the hardness, compared to pure titanium.

  • Titanium-gold alloys are extremely tough and hard and have biomedical applications.

    • There is a constant search for materials for use in orthopaedic medicine and those materials, including titanium alloys, which have a high degree of biocompatibility - that is those that give none or minimal adverse effects on interacting with human tissue.

    • The high biocompatibility and corrosion resistance of Au may yield an alloy suitable for biomedical purposes. In case the machineability decreases with increased hardness, the relatively low melting temperatures of Ti-Au alloys will allow for the majority of parts to be produced by casting in moulds.

    • Ti-Au alloys can adhere to a ceramic surface, making it convenient for a number of biomedical applications, reducing the overall weight and cost of the corresponding parts.

    • Titanium-gold alloys exhibit extreme hardness and strength values, reduced density compared to gold, high malleability, high biocompatibility, low wear, reduced friction, potentially high radio opacity, as well as osseointegration.

      • The term osseointegration refers to the direct structural and functional connection between living bone and the surface of a load-bearing artificial implant i.e. good integration between the natural and artificial materials!

    • All these properties render the Ti-Au alloys particularly useful for orthopaedic, dental, and prosthetic applications, where they could be used as both permanent and temporary components.

  • -

keywords redox reactions ligand substitution displacement balanced equations formula complex ions complexes ligand exchange reactions redox reactions ligands colours oxidation states: titanium ions Ti2+ Ti3+ Ti4+ Ti(+2) Ti(II) Ti(+3) Ti(III) Ti(+4) Ti(IV) TiCl4 + 2Mg ==> Ti + 2MgCl2 or TiCl4 + 4Na ==> Ti + 4NaCl TiO2 + 2Cl2 + C ==> TiCl4 + CO2 TiCl4 + 2Mg ==> Ti + 2MgCl2 or TiCl4 + 4Na ==> Ti + 4NaCl TiCl4 + 2H2O(l) ==> TiO2 + 4HCl TiCl4 + 2Cl–(aq) ==> [TiCl6)]2– [Ti(H2O)6)]3+ [Ti(H2O)6)]2+ Ti3+/Ti2+ oxidation states of titanium, redox reactions of titanium, ligand substitution displacement reactions of titanium, balanced equations of titanium chemistry, formula of titanium complex ions, shapes colours of titanium complexes chemistry of titanium notes for AQA AS chemistry, chemistry of titanium notes for Edexcel A level AS chemistry, chemistry of titanium notes for A level OCR AS chemistry A, chemistry of titanium notes for OCR Salters AS chemistry B, chemistry of titanium notes for AQA A level chemistry, chemistry of titanium notes for A level Edexcel A level chemistry, chemistry of titanium notes for OCR A level chemistry A, chemistry of titanium notes for A level OCR Salters A level chemistry B chemistry of titanium notes for US Honours grade 11 grade 12 chemistry of titanium notes for pre-university chemistry courses pre-university A level revision notes for chemistry of titanium notes  A level guide notes on chemistry of titanium notes for schools colleges academies science course tutors images pictures diagrams for chemistry of titanium notes A level chemistry revision notes on chemistry of titanium notes for revising module topics notes to help on understanding of chemistry of titanium notes university courses in science careers in science jobs in the industry laboratory assistant apprenticeships technical internships USA US grade 11 grade 11 AQA A level chemistry notes on chemistry of titanium notes Edexcel A level chemistry notes on chemistry of titanium notes for OCR A level chemistry notes WJEC A level chemistry notes on chemistry of titanium notes CCEA/CEA A level chemistry notes on chemistry of titanium notes for university entrance examinations

ALPHABETICAL SITE INDEX for chemistry     

Scandium * Titanium * Vanadium * Chromium * Manganese * Iron * Cobalt * Nickel * Copper * Zinc * Silver & Platinum

Introduction 3d–block Transition Metals * Appendix 1. Hydrated salts, acidity of hexa–aqua ions * Appendix 2. Complexes & ligands * Appendix 3. Complexes and isomerism * Appendix 4. Electron configuration & colour theory * Appendix 5. Redox equations, feasibility, Eø * Appendix 6. Catalysis * Appendix 7. Redox equations * Appendix 8. Stability Constants and entropy changes * Appendix 9. Colorimetric analysis and complex ion formula * Appendix 10 3d block – extended data * Appendix 11 Some 3d–block compounds, complexes, oxidation states & electrode potentials * Appendix 12 Hydroxide complex precipitate 'pictures', formulae and equations

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