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CHM 1321 Assignment 1 Answers 1) Draw Lewis structures, showing all unshared electrons, for the following covalent molecules: (a) CH3NH2 (b) CH2CH2 (c) C2H2 H H C C H H

H C C H

(d) CH3CH2CHO

(e) CH3CH2OH2+

(f) (CH3)3N

H H O H C C C H H H

H H H C C O H H H H

H H H C N C H H C H H H H

(g) CH3CN

(h) CH3CH(OH)CH3

(i) CH3NCO

H H C C N H

H H O H H C C C H H H H

H H C N C O H

(j) CH2CHCH(OH)CH2CO2H

(k) NCCH2COCH2CHO

(l) CH3CH(CH3)CH2C(CH2CH3)2CHO

H H C N H H H

H H H H O C C C C C H O H O H H

H O H O N C C C C C H H H

H H C H H C H H H H O H C C C C C H H C H H H H H C H H C H H

(m) (CH3)3C+

(n) CH3CH2O-

(o) CH3CHCHCH2CHCHCOOH

H H C H H H C C H H C H H

H H H C C O H H

H H H H H H O H C C C C C C C O H H H

(p) HC(O)N(CH3)2

H

O C

H H C H N C H H H

1

2) There is a small portion of the periodic table that you must know to do organic chemistry. Construct this from memory including the group numbers, numbers of valence electrons, and electronegativities. I H2.1

III

IV

V

VI

VIII

B2.0 C2.5 N3.0 O3.5 F4.0 Si1.8 P2.1 S2.5 Cl3.0 Br2.8 I2.6

Note: depending on the source you use, small differences exist between electronegativity values. Nevertheless, the relative values for electronegativity are always the same. 3) Draw structures for (a) Two compounds with the formula C4H10 CH3 H2 C

CH3 C H2

H3C

CH H3C

Butane

CH3

2-methylpropane

(b) Three compounds with the formula C3H8O2 (There may be other structures, check with your TA if you are not sure) OH H2 C

HO

OH C H2

C H2

H2 C

HO

CH3

H C

OH

CH 3 OH

1,2-propanediol

1,1-propanediol

H2 C

H3 C

O

C H2

H 3C

CH

HO C H2

1,3-propanediol

H2 C

CH 3 O

O

1,1-diméthoxyméthane

2-Méthoxyéthanol O

CH 3

H 3C

OH C

H 3C

CH HO

CH 3

1-Méthoxyéthanol

OH

2,2-propanediol

2

(c) Two compounds with the formula C2H7N H2 C

H N

H3C

NH2

H3C

CH3

ethylamine N,N-dimethylamine (d) Five compounds of formula C3H6O O H2 C

O

H3C

C

Propanal

C H3C

CH3

Propan-2-one

H

OH

H C

H C

OH C H2

H2C

OH

Prop-2-en-1-ol

C

C H

H3C

H2C

(E)-prop-1-en-1-ol

H2C

O

H2C

CH2

Oxacyclobutane

H2 C

O H2C

CH3

prop-1-en-2-ol

CH

H2C

CH

CH3

OH

2-methyloxirane

Cyclopropanol

4) Name all the compounds in Question 3. Answers in Red. 5) Show the direction of the dipole moments of the following bonds. Use two methods. δ+ δ δ+ δ δ+ δ+ δδC

Cl

δ

δ

C

B

(a) C-Cl

(b) C-H -

(e) C-B

+

(f) N-H

C

C

H

δ-

δ

N

H

N

(c) C-N +

O

(d) C-O

δ

δ

δ+

δ-

O

H

C

Br

-

(g) O-H

C

+

(h) C-Br

3

6) Draw the shape of s and p orbitals including phasing. Show the resulting shapes following sp, sp2 and sp3 hybridization.

p

s

sp

p

s

s

p

s

p

sp2

p

p

p

sp3

7) For each molecule below: i. Draw complete molecular orbital structures using the LCAO method. ii. Label the atomic orbitals used to make the bonds (p, sp, sp2, sp3) iii. Label the bonds (σ, π). iv. Indicate the geometry of each atom (linear, trigonal planar, tetrahedral). (a) CH3CH2NH2 (b) CH3CO2H (c) CH3CHCHCH2CH3 (d) CH3NO2 (f) CH3OCH3

(e) CH3CN

4

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