Document1

CHEMISTRY ASSIGNMENT

PERIODICTABLE

INTRODUCTIO
N

Periodictableisthetabulardisplayofthechemicalelements.The
elementsfollowaregulartrendcalledperiodicity.Todiscussthetrends
basedonthegiventhemesIhavechosenLithium,Fluorine,Carbon,Iron
andBromineelementsbecausetheyarelocatedindifferentgroupsand
periods.Thus,itwillbeeasiertounderstandthetrends
Beforediscussingthethemes,let'sgettoknowthecommontermsthatwill
beused.
1)EffectiveNuclearcharge,Zeff
-thepositivechargeexperiencedbyanelectron
2)Screeningeffect/Shieldingeffect
-thephenomenoncausedbythemutualrepulsionbetweentheinnershell
electronsandtheoutershellelectrons

Elementsingroup&elementsinperiod

Determiningpositionofelementsin
periodictablebasedontheir
electronicconfiguration

Identifythevalence Identifytheblock
electronic

configuration

Highestprincipal Numberofvalence
quantum number,n electrons=group

=period

LITHIUM CARBON
Li:1s²2s1 C:1s22s22p2
Protonnumber:3 Protonnumber:6
Valenceelectron:1 Valenceelectron:4
s-Block p-Block
Group1 Group14
Period2 Period2

BROMINE
Br:1s²2s²2p⁶3s²3p⁶4s²3d104P5

Br:1s²2s²2p⁶3s²3p⁶3d104s24P5

Protonnumber:35
Valenceelectron:7
p-Block
Group17
Period4

FLUORINE
F:1s22s22p5

Protonnumber:9
Valenceelectron:7
p-Block
Group17
Period2

IRON
Fe:1s22s22p63s23p64s²3d6
Protonnumber:26
Valenceelectron:8
d-block
Group8
Period4

ATOMICRADIUS

In1911ErnestRutherfordcarriedoutthegoldfoilexperiment
whichgavescientistanapproximatemeasurementforthesize
oftheatom.Theatomicsizeisthedistancefrom nucleusto
theoutermostshell.However,theradiusofanatom isdifficult
tobedefinedbecausetheelectroncloudhasnoclear
boundary.
Atomicradiusisonehalfofthedistancebetweenthenucleus
oftwocovalentlybondedatoms.

Radius=a(Unit:Angstrom,Å)
2

Li>Fe>Br>C>F
Atomicradiusdecreases
Li>C>F
Elementlithium,carbonandfluorineareinperiod2butindifferentgroup.Size
ofelementlithium islargestwhilesizeofelementcarbonislargerthanfluorine.
Thisisbecauseatomicradiusdecreasesacrosstheperiod.Whentheproton
numberincreases,Zeffalsoincreasesacrosstheperiodbutnumberofshells
remainthesame.So,theattractionbetweennucleusandelectronincreases
causingtheouterelectronstobepulledcloserto

nucleus.Thereforefluorinewiththehighestprotonnumberwillexperience
greaternucleus-electronattractionmeanwhilelithium withleastprotonnumber
experiencesmallestattraction.Therefore,lithium haslargeratomicsize
followedbycarbonandfluorine