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CL 404 : Material
Science
1.Atomic st ructure a nd Interatomic bonding
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Atomic structureAtom : Nucleus (Protons +neutrons) andelectrons
Charge Mass
Proton+ 1.6x10 -19 C 1.67x10 -27 g 1
amu
Neutron
No c!arge 1.67x10-27
g 1amu
electron- 1.6x10 -19 C 9.11x10 -"1 g
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Atomic structureAtom#c Num$er (%): No. o& 'rotons
t g# es t!e c!em#cal #dent#cat#on &or t!eelement
*ass Num$er: No. o& 'rotons neutronst g# es ,ou t!e #dea o& mass o& an atom #n
amu (atom#c mass)
soto'es: no. o& neutrons are d#&&erentAtom#c e#g!t: e#g!ted a erage o&atom#c masses o& t!e atoms naturall,occurr#ng #soto'es
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Atomic structureAtom#c mass un#t (amu): t #s dened as 1/12 o& t!e atom#c mass o& t!e mostcommon #soto'e o& car$on atom t!at !as 6 'rotons and 6neutrons
A agodro s num$er 6.02"x10 2" atoms6.02"x10 2" atoms o& car$on e#g!s 12 g so 1 amu/atom 1 g/mol
x: Atom#c e#g!t o& Cu 6". amu/atom or6". g/mole
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The Bohr Atomic
Model
343P 5!/2
Bohr atomic model:
lectrons re ol e around #n d#screteor$#ts #t! s'ec#c le els o& energ,
!#s model #s not al#d as #t doesn tsat#s&, 8e#sen$erg s uncerta#nt,'r#nc#'le
Class#cal mec!an#cs could not a$le to ex'la#n t!em#crosco'#c $e!a #or #n ol #ng electrons #n sol#ds
uantum mec!an#cs
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Wave –Mechanics model
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lectrons are cons#deredto !a e $ot! a e l#;eand 'art#cle l#;ec!aracter#st#cs
!e 'ro$a$#l#t, o&nd#ng an electron
around t!e nucleus #smax#mum at
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Quantum Numbers=our 'arameters (>uantum num$ers) areneeded to descr#$e t!e d#str#$ut#on and'os#t#on o& electrons #n an atom
Pr#nc#'al >uantum num$er (n) ? s#@e o& an e'dA@#mut!al or angular momentum >uantumnum$er (l) ? s!a'e o& an e'd*agnet#c >uantum num$er (m l) ? s'at#alor#entat#on o& an e'dB'#n >uantum num$er (m s)
electron s 'ro$a$#l#t, dens#t,
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Principal Quantum Number
(n)escr#$es electron s!ells as #n t!e
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Azimuthal/An ular
Quantum Number (l)enes su$or$#tals/su$s!ells l 0 to n-1 (des#gnated $, sD 'DdD&E.)
B!a'e o& t!e or$#tals
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n No. o& su$s!ells Bu$s!ells
1 1 0 (s)2 2 0D1 (sD ')
" " 0D1D2 (sD'Dd)
0D1D2D" (sD'DdD&)
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Ma netic !uantum
number(m l)enes s'at#al or#entat#on (determ#nes t!enum$er o& energ, statesNum$er : -l to +l ( otal num$er : 2l+1)
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Bu$ s!ell No. o& Btates
B 1 (0)
' " (-1D0D1)
d (-2D-1D0D1D2)
& 7 (-"D-2D-1D0D1D2D")
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"pin Quantum number (m s)enes t!e s'#n o& t!e electron
o 'oss#$le s'#ns : B'#n u' (+1/2) and B'#ndo n (-1/2)
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Paul# s xclus#on Pr#nc#'leac! electron state can !old not more t!an
t o electronsD !#c! must !a e o''os#tes#gns
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Total number o# states in
shell/subshell
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n s!ell su$s!ells No. o&states
Num$er o& electrons
Per su$s!ell Per s!ell
1 (l 0) F s 1 2 2
2 (l 0)G
s 1 2 H
2 (l 1) ' " 6
" (l 0)
*
s 1 2 1H
" (l 1) ' " 6
"(l 2) d 10 (l 0)
N
s 1 2 "2
(l 1) ' " 6
(l 2) d 10
(l ") & 7 1
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$lectronic con% urationBe>uence o& ll#ng o& electron or$#tals #s $asedon set o& &ollo #ng rules
Aufbau PrincipleGo er energ, states #ll $e lled rst
Madelung’s ruleIr$#tals ll #n t!e order o& #ncreas#ng (n+l)
s (n+l +0 ) #ll $e lled $e&ore "d ("+2 ) and s ( +0 )
=or or$#tal #t! same alues o& ( n+l )D t!e one #t! lo ern #ll $e lled rst.
"d ("+2 ) #ll $e lled $e&ore '( +1 )Hund’s rule
Num$er o& electrons o& t!e same s'#n #n 'Dd or & statess!ould $e max#mum ( to reduce e - -e - re'uls#on)
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$lectronic con% uration
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Bta$le ? #nertJnsta$le : alence electrons ? res'osn#$le &or c!em#cal
react#on and $ond#ng
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Periodic Table
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Atomic bondin
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Atomic bondin
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Atomic bondinPr#mar, $ond#ng (100 -1000 FL/mol or 1-10eK/atom
on#c $ondCo alent $ond*etall#c $ond
Becondar, $ond#ng (M100 FL/mol or M 1eK/atom)
Kander all &orcePermanent d#'ole #nteract#onPermanent ? #nduced d#'ole #nteract#on=luctuat#ng nduced d#'ole #nteract#ons
8,drogen $ond#ng19
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'onic bondrans&er o& electrons $/ metals and non-
metall#c elementsNon-d#rect#onal
x : NaClIt!er ex: Ca= 2 D CsClD *gID Al 2 I "
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'onic bondin (contd )
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ovalent bondinB!ar#ng o& electronsAtoms o& s#m#lar electronegat# #t,Gocal#@ed ?d#rect#onalAt atom can co alnetl, $ond #t! at mostH-N (N - no. o& alence electrons)
x: Cl 2 molecule C molecule
('ol,et!,leneD et!,leneD d#amond) C8 . molecule =luor#ne
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Metallic bondKalence electrons are not $ound to one 'art#cularatom $ut t!e, &orm a sea (cloud) !#c! #s s!ared$, all t!e atoms
oncore : Pos#t# el, c!argedColum$#c #nteract#on $/ #on core and electroncloudNon ? d#rect#onal
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"tructure+Propert*
relationships*etall#c
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"econdar* bond , van der
Waals #orcePermanent d#'ole moments #n 'olarmolecules due to as,mmetr#calarrangement o& 'os#t# e and negat# e
reg#onsx: 8Cl
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van der Waals #orce
27*olecules #n l#>u#d and gases are !eld $, ea;an der Oaals &orce
Natural osc#llat#on o& atoms ?momentar, $rea;do n o&c!arge s,mmetr,
on can also #nduce d#'ole
#'oles can also #nduce d#'ole
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-*dro en bondin
2H
8#g!est $ond energ, among t!e secondar,$onds
x: 8=D 8 2I
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Wh*.Na #on #s smaller t!an Na atom.*ater#als #t! co alent $onds are lessdenser.
8 $ond#ng #s not &ormed #n 8Cl.ra'!#te 'ossess good lu$r#cat#ng
'ro'ert,.
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