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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. 3d14s2 3d24s2 3d34s2 3d54s1 3d54s2 3d64s2 3d74s2 3d84s2 3d104s1 3d104s2
Electrode potential M(s)/M2+(aq) na –1.63V –1.18V –0.90V –1.18V –0.44V –0.28V –0.26V +0.34V –0.76V
Electrode potential M(s)/M3+(aq) –2.03V –1.21V –0.85V –0.74V –0.28V –0.04V +0.40 na na na
Electrode potential M2+(aq)/M3+(aq) na –0.37V –0.26V –0.42V +1.52V +0.77V +1.87V na na na

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)

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

  • Advanced Inorganic Chemistry Page Index and LinksThe 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


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


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


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Alphabetical Index for Science Pages Content A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

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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