Chapter49Learning goalAfter studying this chapter, you should be able to:•identify positions of the transition metals in the Periodic Table•recognize that most aqueous ions of transition metals are coloured•describe the colours of some transition metal ions such as Fe3+(aq), Cr3+(aq), Cu2+(aq)•describe that transition metals can exist in more than one oxidation states in their compounds,e.g. Fe2+and Fe3+; Mn2+, MnO2and MnO4–•describe that transition metals and their compounds can be used as catalysts•describe the importance of transition metals49.149.249.349.449.549.1What is a transition metal?49.2Coloured ions of transition metals49.3Variable oxidation states of transition metals49.4Catalytic properties of transition metals and theircompounds49.5The importance of transition metals and theircompoundsGeneral properties of transition metals
General properties of transitionmetalsChapter49Potteries are commonly used in making vases, plates and cups. Most potteries are covered by a thincoating of glassy substance known as glaze for strengthening, decorating and waterproofing.Glaze often consists of compounds of transition metals which provide different colours. The finalcolour of a glazed pottery depends on the oxidation states of transition metals and the composition ofglaze. For example, iron has more than one oxidation state and when mixed with different compounds,it can provide red, brown, blue, yellow or green colour.Where can we find transition metals in the Periodic Table?What are the common oxidation states of iron?What are some general properties of transition metals?After studying this chapter, you should be able to answer the above questions.oxidation state氧化態transition metal過渡性金屬glaze釉pottery陶瓷Think about1.We can find transition metals in the central region of the Periodic Table in Periods 4, 5, 6, and 7, in between Groups II and III.2. +2 and +33.Many transition metal ions are coloured in aqueous solution.Most transition metals exhibit variable oxidation states in their compounds.Transition metals and their compounds show catalytic properties.
Positions of transition metals in the Periodic TableIf we look at the Periodic Table, we can find that there is a block betweenGroup II and Group III of the Periodic Table. From Period 4 to Period 7,this block is filled up by 10transition elements(ortransition metals)in each period. See Figure 49.1.49General properties of transition metals349What is a transition metal?49.1Figure 49.1Transition metals occupy the central region of the Periodic Table.21ScScandium20CaCalcium39YYttrium22TiTitanium40ZrZirconium72HfHafnium104RfRutherfordium23VVanadium41NbNiobium73TaTantalum105DbDubnium24CrChromium42MoMolybdenum74WTungsten106SgSeaborgium25MnManganese43TcTechnetium75ReRhenium107BhBohrium26FeIron44RuRuthenium76OsOsmium108HsHassium27CoCobalt45RhRhodium77IrIridium109MtMeitnerium28NiNickel46PdPalladium78PtPlatinum110DsDarmstadtium29CuCopper47AgSilver79AuGold111RgRoentgenium30ZnZinc48CdCadmium80HgMercury112CnCopernicium57LaLanthanum89AcActinium1234567PERIODSIlIIVVVIVII0Grouptransition metal31GaGalliumThetransition metalsoccupy the central region of the PeriodicTable in Periods 4, 5, 6 and 7, in between Groups II and III.
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