1. atomic structure interatomic bonding 1

8/18/2019 1. Atomic Structure Interatomic Bonding 1

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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

12

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)

1"


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$lectronic con% uration

1

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

2"


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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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1. atomic structure interatomic bonding 1

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