Chapter4. Perodic Table

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    Chapter 4Periodic Table of Elements

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    Learning Objectives

    Analyse the Periodic Table of ElementsAnalyse Group 18 elements

    Analyse Group 1 elementsAnalyse Group 17 elementsAnalyse elements in a period

    Understand transition elements

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    A. The Periodic Table of Elements

    Look at these pictures carefully.

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    A. The Periodic Table of Elements

    Why the items in the supermarket or hypermarket are arranged systematically andorderly?

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    A. The Periodic Table of Elements

    Similarly, elements are arranged systematically and orderly.

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    Historical development of the Periodic Table

    Antoine Lavoisier Classify substances into

    metals and non-metalsUnsuccessful because

    light, heat and some other compounds where notelements.

    (1743-1794)

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    Historical development of the Periodic Table

    Johann Dobereiner Introduced triads.Elements were classifiedinto groups of three

    elements with samechemical propertiesThe atomic mass of middleelements was approximately

    the average atomic mass of the other two elements

    (1780-1849)

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    Historical development of the Periodic Table

    John NewlandsArranged elements in order of increasing atomic mass.

    Elements with similar propertiesrecurred at every eight element.This was known as the Law of OctavesFailed because only obeyed by first 17

    elements only

    (1837-1898)

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    Historical development of the Periodic Table

    Lothar Meyer Plotted a graph of the atomicvolume against atomic mass.Elements with similar chemicalproperties occupied samepositions.Successful in showing theproperties of elements formed a

    periodic pattern against their atomic masses.

    (1830-1895)

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    Historical development of the Periodic Table

    Dmitri MendeleevArranged the elements in order of increasing atomic mass.Successful because

    --he left gaps for elements yet to bediscovered. He used the table to predictthe existence and properties of undiscovered elements

    --he change the order of elements of theproperties are not similar.

    (1834-1907)

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    http://en.wikipedia.org/wiki/File:Mendelejevs_periodiska_system_1871.png
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    Historical development of the PeriodicTable

    Henry J. G. Moseley (1887-1915)

    Concluded that proton number shouldbe the bases for the periodic change of chemical propertiesArranged the elements in order of increasing proton number in thePeriodic Table.

    http://www.google.com.my/imgres?imgurl=http://www.glogster.com/media/4/21/1/8/21010805.jpg&imgrefurl=http://www.vegetariansplitpeasoup.com/bg-Moseley-Periodic-Table/&usg=__IljwSG2UGtnwJXH0pqICegtAdM4=&h=393&w=255&sz=15&hl=en&start=5&zoom=1&itbs=1&tbnid=57dfAVAuYuSLfM:&tbnh=124&tbnw=80&prev=/images%3Fq%3DHenry%2BG.%2BJ.%2BMoseley%26hl%3Den%26sa%3DG%26rlz%3D1T4ADSA_enMY385%26biw%3D1276%26bih%3D582%26tbm%3Disch&ei=V_C2Td-GH8vOrQest_jFDQ
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    Modern Periodic Table of Elements

    Elements are arranged according their increasingproton number.Vertical columns = groups (according to their number of valence electron/sHorizontal rows = periods (number of electronshells filled by electrons)

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    Modern Periodic Table of Elements

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    Group 18/VIII Elements

    Known as noble gases/ inert gases(chemically unreactive elements)Non-metals that exist as monoatomic colourless gases.

    Members :Helium (He), Xenon (Xe),Neon (Ne), Radon (Ra).

    Argon (Ar),Krypton (Kr),

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    Physical Properties of Group 18

    Very small atomic sizes.Low melting and boiling points

    Weak Van der Waals forces of attraction between atoms.

    Low densitiesVery small masses but huge volumes.

    Melting and boiling points of elements increasedown the Group 18.

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    Uses of Group 18Elements

    HeliumTo fill airships and weather balloons.

    Airships

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    Uses of Group 18Elements

    Airships

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    Uses of Group 18Elements

    Airships

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    Uses of Group 18 Elements

    Weather balloon

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    Uses of Group 18 Elements

    Weather

    balloon

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    Uses of Group 18 Elements

    Heliumused as artificial atmosphere in oxygen tankfor divers.

    Oxygentank

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    Uses of Group 18 Elements

    Oxygentank

    U f 18

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    Uses of roup 18Elements

    Oxygentank

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    Uses of Group 18 ElementsNeon

    Advertising lights

    U f G 18

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    Uses of Group 18Elements

    NeonUsed in aeroplane runway lights

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    Uses of Group 18 Elements

    KryptonUsed in lasers to repair the retina of the eye.

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    Uses of Group 18 Elements

    KryptonTo fill photographic flash lamps.

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    Uses of Group 18 Elements

    XenonMaking electron tubes and stroboscopic lamps

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    Uses of Group 18 Elements

    XenonUsed in bubble chambers in atomic energyreactors.

    U f G 18

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    Uses of Group 18Elements

    RadonUsed to treat cancer

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    Group 1 ElementsConsists of lithium (Li), sodium (Na), potassium

    (K), rubidium (Rb), caesium (Cs) and francium(Fr).They are known as alkali metals because theyreact with water to produce alkali ne solution.

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    Physical Properties of Group 1 Elements

    SoftLow melting pointsLow densitiesShiny and silvery surfaceGood conductor of heatGood conductor of electricity

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    Physical Properties of Group 1 Elements

    Hardness, melting point andboiling of the elements decrease .

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    Physical Properties of Group 1 Elements

    Hardness, melting point and boiling of the elementsdecrease.

    Metallic bonding in metals is caused by the attractionbetween positive ions and the sea of negative electrons

    surrounding them.

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    Physical Properties of Group 1 Elements

    When go down Group 1, atom becomes larger. The positive nucleus gets

    further away from the negative sea of electrons.

    The force of attraction between the metal ionsand the sea of electrons gets weaker down thegroup.

    Less energy is needed to overcome thisweakening force of attraction.

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    Chemical Properties of Group 1Elements

    All react with water to produce alkaline metalhydroxide solution and hydrogen gas .2X(s) + 2H 2O(l) 2XOH(aq) + H 2(g)

    How to test the alkaline solution?1 542 3

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    Group 1 metals + Wate

    http://brainiac%20alkali%20metals.flv/http://brainiac%20alkali%20metals.flv/
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    Chemical Properties of Group 1Elements

    All burn in oxygen gas to produce white solidmetal oxides .4X(s) + O 2(g) 2X 2O(s)

    The oxide dissolve in water to form alkaline metalhydroxide solution .X2O(s) + H 2O(l) 2XOH(aq)

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    Chemical Properties of Group 1Elements

    All burn in chlorine gas to produce white solidmetal chlorides .

    2X(s) + Cl 2(g) 2XCl(s)

    Alkali metal + water

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    Alkali metal + water Alkali metal Observation Equation

    Lithium (Li) Lithium moves slowly on the water surface with a soft hiss sound. Acolorless solution that turns red litmuspaper blue is formed

    Sodium (Na) Sodium melts to become a smallsphere , moves rapidly and randomly onthe water surface with a soft hiss sound. A colorless solution that turnsred litmus paper blue is formed

    Potassium (K) Potassium melts to become a smallsphere , burns with a lilac flame , very rapidly and randomly on the water surface with a soft hiss and pop sound. A colorless solution that turnsred litmus paper blue is formed

    Alkali metals + Oxygen gas

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    Alkali metals + Oxygen gasAlkali metal Observation Equation

    Lithium (Li) Lithium burns slowly with a red flame andliberates white fumes which become a whitesolid on the cooling to room temperature. Thewhite solid dissolves in the water to produce acolorless solution . This solution turns redlitmus paper blue

    Sodium (Na) Sodium burns rapidly and brightly with ayellow flame and liberates white fumes whichbecome a white solid on the cooling to roomtemperature. The white solid dissolves in thewater to produce a colorless solution . Thissolution turns red litmus paper blue

    Potassium(K)

    Potassium burns very rapidly and brightly witha lilac flame and liberates white fumes whichbecome a white solid on the cooling to roomtemperature. The white solid dissolves in thewater to produce a colorless solution . This

    solution turns red litmus paper blue

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    Alkali metals + Chlorine gasAlkali metal Observation Equation

    Lithium (Li) Lithium burns slowly with a red flame andliberates white fumes which become a whitesolid at the end of the reaction.

    Sodium (Na) Sodium burns rapidly and brightly with ayellow flame and liberates white fumes whichbecome a white solid at the end of thereaction

    Potassium(K)

    Potassium burns very rapidly and brightly witha lilac flame and liberates white fumes whichbecome a white solid at the end of thereaction

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    Chemical Properties of Group 1Elements

    Why all elements in Group 1 have samechemical properties?

    Chemical reaction is all about the activity of electron/sAll the elements have one valence electron .Each of them reacts by donating one valenceelectron to form an ion with a charge of +1 toachieve stable electron arrangement.

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    Reactivity of Group 1 Elements

    Chemical Properties of Group 1

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    Chemical Properties of Group 1Elements

    Why the reactivity of elements increases down the Group 1?Atomic size of Group 1 elements increases from lithium tofrancium./ Number of shells occupied by electrons increases .Distance between the valence electron in the outermost shell andpositive nucleus increases down the Group 1.Attraction between nucleus and valence electron decreases .

    It is easier for the atom to lose the valence electron to achieve stableelectron arrangement.

    Group 17

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    Group 17Elements

    Members are fluorine(F 2) , chlorine(Cl 2),bromine(Br 2), iodine(I 2), and astatine(At 2)

    The elements are also known as halogens which exist as diatomic molecules .

    Physical Properties of Group

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    Physical Properties of Group17

    They have low melting and boiling pointsbecause molecules are attracted to each other by weak van der Waals forces of attraction.

    The melting and boiling points of the elementsincreases down Group 17.This change the states of elements from gas to

    solid and the colour of elements from lighter colour to darker colour.

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    Physical Properties of Group 17

    Elements State Colour

    Fluorine Gas Pale yellow

    Chlorine Gas Greenish-yellowBromine Liquid Reddish-brown

    Iodine Solid Purplish-black

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    Physical Properties of Group 17

    Why the melting and boiling points of elementsincreases down Group 17?

    Molecular size/relative molecular mass of the

    elements increases down Group 17.Forces of attraction betweenmolecules/Intermolecular forces of attractionincreases .

    More heat is needed to overcome the stronger forcesof attraction between the molecules.

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    Chemical Properties of Group 17

    All members have similar chemical properties but differ inthe reactivity.

    React with water to form two acids

    X2(g) + H

    2O(l) HX(aq) + HOX(aq)

    Example:

    Cl2(g) + H 2O(l) HCl(aq) + HOCl(aq)

    hydrochloric hypochlorousacid acid

    Hypochlorous acid is a bleaching agent (bleach both blue and redlitmus paper)

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    Chemical Properties of Group 17

    All members have similar chemical properties but differ inthe reactivity.

    Halogens in gaseous state react with hot iron to form brownsolid.2Fe(s) + 3X 2(g) 2FeX 3(s)

    Example:

    2Fe(s) + 3Cl 2(g) 2FeCl 3(s)

    solid iron(III) chloride(brown)

    Chemical Properties

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    Chemical Propertiesof Group 17

    All members have similar chemical properties but differ in the reactivity.

    Halogens react with sodium hydroxide solution to producesodium halide, sodium halate(I) and water X2 + 2NaOH(aq) NaX(aq) + NaOX(aq) + H 2O(l)

    Example:

    Cl2 + 2NaOH(aq) NaCl(aq) + NaOCl(aq) + H 2O(l)

    Sodium chlorate(I)

    Chemical Properties

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    Chemical Propertiesof Group 17

    Why all halogens possess similar chemicalproperties?Chemical reaction = lose or accept electron/sAll halogens always gain one electron to achievestable octet electron arrangement.Therefore, they have similar chemical properties.

    Chemical Properties

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    Chemical Propertiesof Group 17

    Why chemical reactivity of halogens decreasesdown Group 17?Atomic size/number of electron occupied shells of halogens increases down Group 17.The outermost shell becomes further from thenucleus of the atom.

    Strength to attract one electron into the outermostshell by the nucleus becomes weaker.Reactivity decreases.

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    PeriodElements across a period exhibit a periodic changein properties.Period 3Proton number increases by one unit from oneelement to the next element

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    PeriodAll the atoms of the elements have three shellsoccupied with electronsThe number of valence electrons in each atomincrease from 1 to 8

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    PeriodAll the elements exist as solid except chlorine andargon which are gasesThe atomic radius of elements decreases. This isdue to the increasing nuclei attraction on thevalence electrons.

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    PeriodThe electronegativity of elements increases. Thisis also due to the increasing nuclei attraction onthe valence electrons and the decreases in atomic

    size.

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    Period

    Metals Metalloid Non-metalsMetalloid semi-metal, reacts with acid only, weakconductor, brittle and not malleable and ductile.

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    PeriodUses of metalloid

    Make diodes and transistorsA diode A transistor

    Both are commonly used in the making of microchipsMicrochips are widely used in the manufacture of computers,mobile phones, televisions, video recorders, calculators, radio andetc.

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    PeriodOxides of elements change from basic to amphoteric andthen to acidic across the period towards the right.

    Basic oxides react with acids to form salt and water Acidic oxides react with alkalis to form salt and water Amphoteric oxides react with both acids and alkalis toform salt and water.

    Transition

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    TransitionElements

    Elements from Group 3 to Group 12 in the PeriodicTable.Common characteristics

    Solid metal with shiny surface.Good conductor of heat and electricity.High melting and boiling points.

    Hard, malleable and ductile.

    Transition

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    TransitionElements

    Special characteristicsAll are metalsShow different oxidation numbers in their compoundsForm coloured ions or compoundsUse as catalysts

    Form complex ions

    Transition

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    TransitionElements

    Show different oxidation numbers in their compound

    Compound Formula Oxidation number

    Chromium(III) chloride Cr Cl3

    +3

    Potassium dichromate(VII) K 2Cr 2O 7 +6

    Manganese(II) sulphate MnSO 4 +2

    Manganese(VI) oxide MnO 2 +4

    Potassium manganate(VII) K MnO 4 +7

    Iron(II) sulphate Fe SO 4 +2

    Iron(III) chloride Fe Cl3 +3

    Copper(I) oxide Cu 2O +1

    Copper(II) sulphate Cu SO 4 +2

    Transition

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    TransitionElements

    Form coloured ions or compoundsElement Ion Colour

    Chromium Cr 3+ Green

    CrO 42- Yellow

    Cr 2O 72- Orange

    Manganese Mn 2+ Pale pink

    MnO 4- Purple

    Iron Fe 2+ Pale green

    Fe 3+ Yellowish brown

    Cobalt Co 2+ Pink

    Nickel Ni 2+ Green

    Copper Cu 2+ Blue Green

    Transition

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    TransitionElements

    Form coloured ions or compoundsGemstone Transition metal Colour

    Emerald Ni and Fe Green

    Amethyst Fe and Mn Purple

    Sapphire Co and Ti Blue

    Ruby Cr Red

    Topaz Fe Yellow

    Transition

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    TransitionElements

    Emerald

    Transition

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    TransitionElements

    Amethyst

    Transition

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    TransitionElements

    Sapphire

    Transition

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    TransitionElements

    Ruby

    Transition

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    TransitionElements

    Topaz

    Transition

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    TransitionElements

    As catalyst

    Process Catalyst Tomanufacture

    Haber Process Iron fillings, Fe Ammonia

    ContactProcess

    Vanadium(V)oxide, V 2O 5

    Sulphuric acid

    OstwaldProcess

    Platinum, Pt Nitric acid

    Hydrogenation Nickel, Ni Margarine

    Transition

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    TransitionElements

    To form complex ions

    Element Complex ions Formula

    Iron Hexacyanoferrate(II) ion [Fe(CN)6]4-

    Hexacyanoferrate(III) ion [Fe(CN) 6]3-

    Chromium Hexaamina chromium(III) ion [Cr(NH 3)6]3+

    Copper Tetraamina copper(II) ion [Cu(NH 3)4]2+

    Tetrachlorocuprate(II) ion [CuCl 4]2-