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Elements in a PeriodElements in a Period

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Periodic Table consists of 7 periodsPeriodic Table consists of 7 periods

( Period 1 to Period 7 ).( Period 1 to Period 7 ).Period numberPeriod numberis theis the number of shellsnumber of shells

occupied with eoccupied with e..

When across a period from left to right,When across a period from left to right,-- proton numberproton number& number of valence e& number of valence e

increase by 1increase by 1 from one element to thefrom one element to the

next.next.

-- both physical & chemical propertiesboth physical & chemical properties

change in a certain pattern.change in a certain pattern.

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Change in properties across Period 3Change in properties across Period 3

ElementElement NaNa MgMg AlAl SiSi PP SS ClCl ArAr

Proton numberProton number 1111 1212 1313 1414 1515 1616 1717 1818

ee arrangementarrangement 2.8.12.8.1 2.8.22.8.2 2.8.32.8.3 2.8.42.8.4 2.8.52.8.5 2.8.62.8.6 2.8.72.8.7 2.8.82.8.8

Atomic radius /Atomic radius /

pmpm

186186 160160 143143 118118 110110 104104 100100 9494

ElectronegativityElectronegativity 0.90.9 1.21.2 1.51.5 1.81.8 2.12.1 2.52.5 3.03.0 --

Metallic propertyMetallic property MetalsMetals semisemi NonNon--metalsmetals

MP /MP / CC 9898 649649 660660 14111411 4444 113113 101101 189189

BP /BP / CC 886886 10901090 24672467 23552355 280280 444444 3535 186186

Physical statePhysical state solidsolid gasgas

ElectricalElectrical

conductivityconductivity

goodgood weakweak Cannot conductCannot conduct

electricityelectricity

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Across Period 3,Across Period 3,

atomic sizeatomic size

All atoms of elements in Period 3 haveAll atoms of elements in Period 3 have3 shells3 shellsoccupied with eoccupied with e. Across the period from left to. Across the period from left to

right, theright, thenumber of protons & electronsnumber of protons & electrons..This causes theThis causes theattraction by nucleus on eattraction by nucleus on e

becomes stronger & pull the ebecomes stronger & pull the ecloser to nucleus.closer to nucleus.

Therefore, the atomic sizeTherefore, the atomic size across Period 3.across Period 3.

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Across Period 3,Across Period 3,

ElectronegativityElectronegativity

TheTheincrease in positive charge ( protonsincrease in positive charge ( protons) of) of

the nucleus &the nucleus &decrease in the atomic sizedecrease in the atomic sizecause the strength of nucleus to attract ecause the strength of nucleus to attract e

toto.. Therefore, electronegativityTherefore, electronegativity..

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Across Period 3,Across Period 3,

Physical state change fromPhysical state change from solid tosolid to

gasgas

SodiumSodium sulphursulphurarearesolidssolidsdue to highdue to highmelting & boiling points.melting & boiling points.

Chlorine & ArgonChlorine & Argonarearegasesgasesbecause theirbecause their

melting & boiling points are low.melting & boiling points are low.

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Across Period 3,Across Period 3,

Metallic propertiesMetallic properties

**Elements on the left (Elements on the left (NaNaAlAl) are) aremetals.metals.

They conduct electricity.They conduct electricity.

*E

lements on the right (*E

lements on the right (PPArAr) are) arenonnon--metals.metals. They cannot conduct electricity.They cannot conduct electricity.

**SiSi semisemi--metal / metalloidsmetal / metalloids shows bothshows bothmetallic & nonmetallic & non--metallic properties.metallic properties.

Si is a weak conductor of electricity. ElectricalSi is a weak conductor of electricity. Electricalconductivityconductivity with the presence of boron /with the presence of boron /phosphorus.phosphorus.

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Properties of oxides of elements inProperties of oxides of elements in

Period 3Period 3MetalsMetals formform oxidesoxides withwith basicbasic

properties.properties.

NonNon--metalsmetals form oxides withform oxides with acidicacidicproperties.properties.

AlAl22OO33 exhibit both basic & acidicexhibit both basic & acidic

propertiesproperties known asknown as amphotericamphotericoxides.oxides.

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OxideOxide

ObservationObservation

WithWith NaOHNaOH solutionsolution WithWith HNOHNO33 solutionsolutionAlAl22OO33 White powderWhite powder

dissolvesdissolves to formto form

colourless solutioncolourless solution

White powderWhite powder

dissolvesdissolves to formto form

colourless solutioncolourless solution

MgOMgO No change.No change. White powder White powder

dissolves to formdissolves to form

colourless solutioncolourless solution

SiOSiO22 White powderWhite powderdissolves to formdissolves to form

colourless solutioncolourless solution

No change.No change.

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Oxides ofOxides of

element inelement inPeriod 3Period 3

NaNa22OO

MgOMgO

AlAl22OO33 SiOSiO22 , P, P44OO1010 ,,

SOSO22 , Cl, Cl22OO77

PropertiesProperties

of oxideof oxide

BasicBasic AmphotericAmphoteric AcidicAcidic

Al2O3 (s) + 6HNO3 (aq) 2Al(NO3)3 (aq) + 3H2O (l)

Al2O3 (s) + 2NaOH (aq) 2NaAlO2 (aq) + 3H2O (l)

sodium aluminate

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Uses of semiUses of semi--metalsmetals

SiliconSilicon weak conductor of electricity butweak conductor of electricity but

thethe conductivityconductivity with the in temperature with the in temperature..

Si when doped withSi when doped with phosphorusphosphorus // boronboron, it, itbecomes a good conductor of electricity,becomes a good conductor of electricity,

known asknown as semiconductor.semiconductor.

Semiconductor only allows electric currentSemiconductor only allows electric current

to flow in one direction & is used to maketo flow in one direction & is used to make

diodes, transistorsdiodes, transistors etc.etc.

Germanium used in microelectronicGermanium used in microelectronic

industry.industry.

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Transition elementsTransition elements

Group 3 to Group 12.Group 3 to Group 12.

All transition elements are metals.All transition elements are metals.

Solids with shiny surfaces.Solids with shiny surfaces.

High melting & boiling points.High melting & boiling points.

High densities.High densities.

Good conductor of heat & electricity.Good conductor of heat & electricity.

High tensile strengthHigh tensile strength ( stay in their shape without( stay in their shape without

breaking when force is applied to it ).breaking when force is applied to it ).

DuctileDuctile (able to be stretched ) &(able to be stretched ) & malleablemalleable (able(able

to be bent ).to be bent ).

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SpecialSpecial

Properties ofProperties ofTransitionTransition

ElementsElements

Form coloured ions /coloured ions /

compoundscompounds (gemstones)

Exhibit differentdifferent

oxidation numbersoxidation numbers in

compounds

Form complexcomplex

ionion

Act as a catalystcatalyst

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(a)(a) Form coloured ions / compoundsForm coloured ions / compounds

IonsIons Formula ionFormula ion colour colour

Copper (II)Copper (II) CuCu2+2+ blueblue

Iron (II)Iron (II) FeFe2+2+ Pale greenPale green

Iron (III)Iron (III) FeFe3+3+ brownbrown

Cobalt (II)Cobalt (II) CoCo2+2+ pinkpink

Nickel (II)Nickel (II) NiNi2+2+ greengreen

Chromium (III)Chromium (III) CrCr3+3+ greengreen

Manganese (II)Manganese (II) MnMn2+2+ Light pinkLight pinkManganate (VII)Manganate (VII) MnOMnO44

-- purplepurple

Chromate (VI)Chromate (VI) CrOCrO4422-- yellowyellow

Dichromate (VI)Dichromate (VI) CrCr22OO7722--

orangeorange

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(b)(b) Exhibit different oxidation numbersExhibit different oxidation numbers

Oxidation numberOxidation number charge on thecharge on theelement.element.

Transition elementTransition element Oxidation numberOxidation number

IronIron +2 , +3+2 , +3

NickelNickel +2 , +3+2 , +3

CopperC

opper +1 , +2+1 , +2ManganeseManganese +2 , +3 , +4, +6 , +7+2 , +3 , +4, +6 , +7

ChromiumChromium +2 , +3 , +6+2 , +3 , +6

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(c)(c) Form complex ionsForm complex ions

Complex ionComplex ion biggerbigger--sizedsized polyatomic ionpolyatomic ionformed when molecules / ions bonded to aformed when molecules / ions bonded to a

central transition metal ion.central transition metal ion.

Examples :Examples :

Hexacyanoferrate (II) ion, [ Fe(CN)Hexacyanoferrate (II) ion, [ Fe(CN)66 ]]44--

Hexacyanoferrate (III) ion, [ Fe(CN)Hexacyanoferrate (III) ion, [ Fe(CN)66 ]]33--

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(d)(d)Act as a catalystAct as a catalyst

CatalystCatalyst substance thatsubstance that alters the rate ofalters the rate ofreactionreaction but isbut is not consumed in thenot consumed in the

reaction.reaction.

ReactionsReactions CatalystCatalysthydrogenationhydrogenation NiNi

Zn + HZn + H22SOSO44 CuSOCuSO44

Decomposition of HDecomposition of H22OO22 MnOMnO22Haber processHaber process FeFe

Contact processContact process VV22OO55

Ostwald processOstwald process PtPt

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Words themselves have notangible weight, but a careless

remark can weight peoples

hearts down.

~ Still Thoughts