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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