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Chapter 2: Molecular
Representations
What's Covered? Bond-line and 3D representations of structures O Constitutional isomers Functional groups and physical properties Resonance structures e Curved arrows
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2haPte6 Z:- Nideo notes
Ways to Represent Molecules
Review: Lewis Dot Structures/Partially Condensed Structures/ Constitutional Isomers CH3-CH2-CHz-CH2-CH3 Bond Line: covalent bonds are represented with a zig-zag line. The end of a line represents a carbon atom with hydrogen atoms to complete the octet. O, N, S, Xiwith hydrogen and electrons are included. Include formal charges where applicable.
HDI
Degree of Unsaturation/Hydrogen Deficiency Index equation =2+2#C-#H-#X+#N
2
O all single 1doubleorring 2 multiple double/ring or triple
4 benzene
3 multiple bonds/rings
Ways to Represent Molecules
Example: Draw the constitutionallsomers for the molecular formula,C,HO using the partially condensed structure and bond line structure Degree of Unsaturation = 2+(2x>)-%=Q=O Al singie
Partially Condensed:
Bond Line:
OF
CH3-CHz-CHz-OH 7 3
.OH
I0H
CH-CH-CH3 2 3 CH3-O-CHz-CH3 Try it On Your Own! Give the condensed structure for each bond line formula What would the degree of unsaturation be for each?
4=0 CK3
CHz-CH-ChzCH-CHz-MHg SHg Du=O CH z-CH C4z-CHf-atz Du=O HS
Answer: Try it On Your Own!
Give the condensed structure for each bond line formula What would the degree of unsaturation be for each?
chr 1
H S- CHz
HS
chy CI
CI
Ou=6
Identifying Functional Groups:
TABLE 2.1 EXAMPLES OF COMMON FUNCTIONAL GROUPS FUNCTIONAL GROUP* CLASSIFICATION EXAMPLE R-X: Alkyl halide 3 towaxas X=CI, Br,orI) C3HqcI Alkene u3z 1-Butene gu=1 CuHS R-CECR Alkyne
Du=2 R-OHY
1-Butyne CyH6 H+ 1-Butanol H-bondiny
Alcohol