CHEM 141 Exam 3 2025 Questions and Answers

CHEM 141 Exam 3 2025 Questions and
Answers


Covalent Bonds - --CORRECT ANSWER---Valence electrons of one atom

attracted to nucleus of other atom

-Electrons are located between nuclei

-Bond formation lowers the PE of the system and stabilizes the system.

Why is carbon so important? - --CORRECT ANSWER---Forms four bonds.

-Can bond with C,H,O,N,S,P

-Properties of these compounds are emergent.

Valence Bond Theory - --CORRECT ANSWER---The idea that covalent bonds

are formed when orbitals of different atoms overlap

CH4 forms ____________ orbitals - --CORRECT ANSWER--hybridized; sp3

hybridization on the carbon atom

Draw CH4 - --CORRECT ANSWER--

Drawing Lewis Structures (rules) - --CORRECT ANSWER--1. Sum of valence

electrons.


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, 2. draw skeleton structure.

3. Use 2 e- for each bond.

4. Make sure each atom (except H) has 8 electrons by adding lone pairs.

5. If there are not enough electrons form multiple bonds.

What is an isomer? - --CORRECT ANSWER--molecules that have the same type

and number of atoms but are bonded together in a different arrangement.

Generic hydrocarbon formula - --CORRECT ANSWER--C(n)H(2n+2)

Sigma bonds allow ___________ __________ of the bonded atoms - --

CORRECT ANSWER--free rotation

Sigma bond - --CORRECT ANSWER--

Pi bond - --CORRECT ANSWER--Whenever pi bond is present, then so is sigma

bond.

Alkenes - --CORRECT ANSWER---Hydrocarbons with one or more carbon-

carbon double bonds.

-One sigma bond, one pi bond.

- Restricted rotation around the double bond.

-C is sp2 hybridized.

Triple Bonds - --CORRECT ANSWER---C - sp hybridized



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