Aula 7 Geometria Molecular 2pp

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GEOMETRIA MOLECULAR 
E POLARIDADE
Profa.: Eliane Sloboda Rigobello
POLARIDADE�DAS�
LIGAÇÃOS�COVALENTES
RELEMBRANDO....
3RGH�VH GHWHUPLQDU R WLSR GH OLJDomR DWUDYpV GR FiOFXOR GD GLIHUHQoD
GH HOHWURQHJDWLYLGDGH �'(��
(OHWURQHJDWLYLGDGH H�7LSR�GH�/LJDomR
�
(P�JHUDO��D�OLJDomR�p��
,{QLFD��VH�D�GLIHUHQoD�GH�HOHWURQHJDWLYLGDGH p�!����
&RYDOHQWH��VH�D�GLIHUHQoD�GH�HOHWURQHJDWLYLGDGH p������
/LJDomR��
&RYDOHQWH�����������������������������&RYDOHQWH ,{QLFD
$SRODU 3RODU
LIGAÇÃO COVALENTE APOLAR: quando
dois átomos com eletronegatividades próximas
ou semelhantes formam uma ligação
covalente.
Ex: HǦH, FǦF, CH4, etc
LIGAÇÃO COVALENTE POLAR: quando dois
átomos de eletronegatividades diferentes formam
uma ligação covalente, os elétrons não são
compartilhados igualmente por eles. O átomo de
maior eletronegatividade atrai o par de elétron
para mais perto de si, resultando num dipolo.
Ex: HǦF, OǦH, NǦH, CǦO, CǦCl, etc
3RODULGDGH�GDV�/LJDo}HV�&RYDOHQWHV
�
/LJDomR�&RYDOHQWH�3RODU��0RPHQWR�GH�'LSROR
8PD OLJDomR SRODU WHP XP GLSROR� RX VHMD� XP GRV iWRPRV WHP
FDUJD SDUFLDO SRVLWLYD �GG�� H R RXWUR �PDLV HOHWURQHJDWLYR� XPD
FDUJD SDUFLDO QHJDWLYD �G��� 8PD VHWD LQGLFD R VHQWLGR
GD SRODUL]DomR GD OLJDomR�
$ LQWHQVLGDGH GR GLSROR GH XPD OLJDomR p GDGD SHOR PRPHQWR
GH GLSROR HOpWULFR �P��
_P_� �T�G��'��'HE\H�
4XDQWR�PDLV�SRODU�XPD�OLJDomR��PDLRU�VHX�
PRPHQWR�GH�GLSROR�
�
7HRULD�GH�
/LJDomR�
53(&9
7HRULD�GH�
/LJDomR�
/9
7HRULD�GH�
/LJDomR�
20
TEORIAS DE LIGAÇÃO COVALENTE
6
*HRPHWULD GDV PROpFXODV
Æ 3RGH LQWHUIHULU VLJQLILFDWLYDPHQWH QDV
SURSULHGDGHV ItVLFDV H TXtPLFDV GDV VXEVWkQFLDV�
&RPR�SUHYHU�D�
JHRPHWULD�GH�XPD�
PROpFXOD"
0RGHOR�53(&9��
7HRULD�GH�OLJDomR�GD�
UHSXOVmR�GRV�SDUHV�GH�
HOpWURQV�GD�FDPDGD�GH�
YDOrQFLD
3DUD�R�DUUDQMR�HVSDFLDO�GRV�iWRPRV�HP�XPD�PROpFXOD��RV�SDUHV�
GH�HOpWURQV��GH�YDOrQFLD�VH�UHSHOHP�PXWXDPHQWH�HP�WRUQR�GR�
iWRPR�FHQWUDO��GH�IRUPD�D�PLQLPL]DU�D�UHSXOVmR�HOHWU{QLFD�
7
GEOMETRIA MOLECULAR
1� 'HVHQKDU D HVWUXWXUD GH /HZLV�
�� 'HWHUPLQDU R Q~PHUR GH UHJL}HV GH GHQVLGDGH HOHWU{QLFD RX
GRPtQLRV GH HOpWURQV �1'� DR UHGRU GR iWRPR FHQWUDO�
�� 2 1' GR iWRPR FHQWUDO GHWHUPLQD D JHRPHWULD GR DUUDQMR HOHWU{QLFR
�JHRPHWULD HOHWU{QLFD� � 53(&9�
�� 3DUD GHWHUPLQDU D JHRPHWULD PROHFXODU FRQVLGHUH DSHQDV DV
OLJDo}HV DR iWRPR FHQWUDO �SDUHV OLJDQWHV��
8
GEOMETRIA DE MOLÉCULAS 
POLIATÔMICAS - MODELO RPECV
1'� �
SDUHV�GH�H� OLJDQWHV
�
SDUHV�GH�H� QmR OLJDQWHV
™ ([HPSORV�
)yUPXOD
9
Determinação do número de domínios de 
elétrons
&2� 1+�
1'
(VWUXWXUD�GH�/HZLV
ÈWRPR�FHQWUDO
1~PHUR�GH�iWRPRV�
OLJDGRV�DR�iWRPR�FHQWUDO
3DUHV�GH�HOpWURQV�QmR�OLJDQWHV�
VREUH�R�iWRPR�FHQWUDO
Teoria de Ligação VSEPR
™&RQVLGHUH�DV�VHJXLQWHV�PROpFXODV�RX�tRQV�SROLDW{PLFRV�FRPR�H[HPSORV�
Fórmula:
Estrutura�de�Lewis:
Átomo�central
Número�de�átomos�ligados�ao�
átomo�central
Número�de�pares�isolados�de�
elétrons�sobre�o�átomo�central
Número�total�de�regiões�de�alta�
densidade�eletrônica�sobre�o�
átomo�central
���ž
GEOMETRIA MOLECULAR
�����ž
GEOMETRIA MOLECULAR
��ƒ�����ƒ��
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GEOMETRIA MOLECULAR
14
��ƒ�����ƒ
GEOMETRIA MOLECULAR
Exemplo 1: Qual a geometria da H2O?
0e72'2�53(&9
���(VWUXWXUD�GH�/HZLV�
�� 1'� �
���*HRPHWULD HOHWU{QLFD��
���*HRPHWULD PROHFXODU�
��UHJL}HV�GH�GHQVLGDGH�HOHWU{QLFD�
ILFDP�R�PDLV�GLVWDQWHV�SRVVtYHO�
HQWUH�VL��53(&9��FRP�kQJXOR�GH�
�����ž��WHWUDHGUR�
H:O:H
..
..
15
���� ��
WHWUDpGULFD
DQJXODU
Geometria Molecular
™ &RPR D JHRPHWULD GD DP{QLD p XP IUDJPHQWR GD JHRPHWULD
WHWUDpGULFD SRGHUtDPRV HVSHUDU XP kQJXOR GH OLJDomR +�1�+
SUy[LPR GH �����ƒ� 1R HQWDQWR� HP 1+�� RV kQJXORV VmR GH
�����ƒ� 3RU TXH RFRUUH HVWH GHVYLR"
8P SDU LVRODGR GH HOpWURQV RFXSD PDLV HVSDoR GR TXH
SDUHV OLJDQWHV� $VVLP� DV UHSXOV}HV HQWUH SDUHV QmR
OLJDQWHV �S1/� H SDUHV OLJDGRV �SO� HVWmR QD RUGHP�
pNL/pL >> pl/pl
5HSXOV}HV�
S1/�SO PDLV�
IRUWHV�GR�TXH�
UHSXOV}HV�SO�SO
16
0ROpFXODV�FRP�PDLV�GH�XP�iWRPR�FHQWUDO�H�SDUHV�LVRODGRV�GH�
HOpWURQV
¾ ([HPSOR��PHWDQRO��&+�2+��
¾ 3RGHPRV GLYLGLU D PROpFXOD GH PHWDQRO HP GXDV UHJL}HV
�YHUPHOKR H D]XO�
17
Geometria Molecular
(VWUXWXUD�GH�/HZLV���
¾'H DFRUGR FRP D WHRULD 96(35� FDGD iWRPR
FHQWUDO GH & WHP TXDWUR UHJL}HV GH DOWD
GHQVLGDGH HOHWU{QLFD� SRUWDQWR� DSUHVHQWD
geometria eletrônica tetraédrica� &RPR QmR Ki
SDUHV LVRODGRV GH HOpWURQV QR iWRPR GH &� D
geometria molecular p WDPEpP tetraédrica�
*HRPHWULD��PROHFXODU�GH�FRPSRVWRV�FRQWHQGR�GXSODV�OLJDo}HV
™ ([HPSOR� HWLOHQR �&�+��
™ 'H DFRUGR FRP D WHRULD 53(&9� H[LVWHP três regiões de alta
densidade eletrônica (3 domínios ligantes) DR UHGRU GH FDGD
iWRPR GH FDUERQR H SRUWDQWR VXD geometria eletrônica é
trigonal plana� &RPR QmR H[LVWHP SDUHV LVRODGRV GH HOpWURQV
VREUH RV iWRPRV GH FDUERQR D geometria molecular WDPEpP p
trigonal plana.
18
Geometria Molecular
(VWUXWXUD�GH�/HZLV�
*HRPHWULD��PROHFXODU�GH�FRPSRVWRV�FRQWHQGR�WULSODV�OLJDo}HV
™ 'H DFRUGR FRP D WHRULD 53(&9� H[LVWHP duas regiões de alta
densidade eletrônica (dois domínios ligantes) DR UHGRU GH FDGD
iWRPR GH FDUERQR H SRUWDQWR VXD geometria eletrônica é linear�
&RPR QmR H[LVWHP SDUHV LVRODGRV GH HOpWURQV VREUH RV iWRPRV
GH FDUERQR D geometria molecular WDPEpP p linear.
19
Geometria Molecular
™ ([HPSOR� DFHWLOHQR �&�+��
(VWUXWXUD�GH�/HZLV�
PRPHQWR�GH�GLSROR� ��
�PROpFXOD�DSRODU�
‰ 3DUD XPD PROpFXOD SROLDW{PLFD FRP PDLV GR TXH GRLV iWRPRV
OLJDGRV SRU OLJDo}HV SRODUHV� QyV GHYHPRV FRQVLGHUDU R DUUDQMR GRV
GLSRORV GH OLJDomR UHVXOWDQWHV SDUD GHFLGLU VH D PROpFXOD p SRODU�
‰ 9DPRV FRQVLGHUDU XPD PROpFXOD FRP D IyUPXOD $%�� TXH SRGH WHU
GXDV JHRPHWULDV PROHFXODUHV�
‰ 6XSRQKD�TXH�%�VHMD�PDLV�HOHWURQHJDWLYR�TXH�$��(QWmR�D�OLJDomR�$�%�p�
SRODU�FRP�D�FDUJD�SDUFLDO�QHJDWLYD�VREUH�%��1yV�SRGHPRV�YHU�FDGD�GLSROR�
GH�OLJDomR�FRPR�XP�vetor eletrônico��FRP�uma magnitude H�GLUHomR�
0RPHQWR�GH�GLSROR�!��
�PROpFXOD�SRODU� 20
Polaridade x Geometria Molecular
Exemplo: água (H2O) - Molécula Polar
8PD VHWD LQGLFD R VHQWLGR GD
SRODUL]DomR GD OLJDomR RX PRPHQWR GH
GLSROR UHVXOWDQWH
$ SRODULGDGH GD PROpFXOD p D VRPD YHWRULDO
GRV PRPHQWRV GH GLSROR GH WRGDV DV
OLJDo}HV
2V SDUHV GH HOpWURQV LVRODGRV QR R[LJrQLR
FRQWULEXHP DLQGD PDLV SDUD D SRODULGDGH GD
iJXD�
21
&+�
/LJDo}HV�+�&�+�
kQJXORV� ������ƒ
&)�
/LJDo}HV�)�&�)�
kQJXORV� ������ƒ
7HRULD 53(&9
*HRPHWULD HOHWU{QLFD H PROHFXODU 7(75$e'5,&$ ± TXDWUR UHJL}HV GH
DOWD GHQVLGDGH HOHWU{QLFD �]HUR SDUHV GH HOpWURQV QmR OLJDQWHV�
22
Geometria Molecular
*HRPHWULD�(OHWU{QLFD�7HWUDpGULFD��(VSpFLHV�$%�
�6HP�3DUHV�,VRODGRV�GH�(OpWURQV�VREUH�$�
™ 3DODULGDGH GR &+� H &)�
™Polaridade CH3F e CH2F2ÆÆ a adição de dipolos desiguais torna a molécula polar
0RPHQWR�GH
GLSROR� ���
0RPHQWR�GH
GLSROR� ���
0RPHQWR�GH
GLSROR�!���
0RPHQWR�GH
GLSROR�!���
23
Geometria Molecular
Regras para Determinação da Geometria 
Molecular
(VFUHYD�D�
HVWUXWXUD�GH�
/HZLV�H�
LGHQWLILTXH�R�
iWRPR�FHQWUDO
&RQWH�R�Q~PHUR�
GH�UHJL}HV�GH�
DOWD�GHQVLGDGH�
HOHWU{QLFD�VREUH�
R�iWRPR�FHQWUDO
'HWHUPLQH�D�
geometria
eletrônica DR�
UHGRU�GR�iWRPR�
FHQWUDO
'HWHUPLQH�D�
geometria
molecular DR�
UHGRU�GR�iWRPR�
FHQWUDO
'HWHUPLQDU�R�
PRPHQWR�GH��
GLSROR��PP�
™ $JRUD TXH FRQKHFHPRV D WHRULD GH OLJDomR 53(&9 H SRODULGDGH
GDV PROpFXODV SRGHPRV XWLOL]DU RV SDVVRV GHVFULWRV DEDL[R SDUD
GHWHUPLQDU D JHRPHWULD PROHFXODU
24
Apolar
Polar
P ��
P !��
([HUFtFLRV�
�� 3DUD�FDGD�XPD�GDV�HVSpFLHV�DEDL[R�
D� 'HWHUPLQH�R�1'�
E� 4XDO�D�JHRPHWULD�HOHWU{QLFD�H�PROHFXODU�GD�HVSpFLH"
,� +�6 ,,� 3+� ,,,��+2&O ,9� 62�
9��$O&O� 9,� &&O�� 9,,��62�
9,,,��&+�� ,;��&+��
�� $V PROpFXODV DEDL[R VmR SRODUHV RX DSRODUHV" 0RVWUH R GLSROR
IRUPDGR HP FDGD OLJDomR H R UHVXOWDQWH �TXDQGRD PROpFXOD IRU
SRODU��
D��+%U E��1+� F��%U� G��2�
H��+�2����������������I��%)�
25