CHEM 2261: Exam 1 Review Tamara Nauman Louisiana State University

CHEM 2261: Exam 1 Review Tamara Nauman 2025-
2026 Louisiana State University




Topics Covered: Formal
Charge
Electrophilicity & Nucleophilicity
Functional Groups & Substituents
Alkyl Substitution
Polarity Naming
Acidity & Basicity Boiling
Point & Melting Point
Resonance
Lewis Structures & Molecular Geometry Isomers

, Topic 1: Formal Charge

*Valence electrons – electrons assigned = formal charge*

1) Which of the following molecules/ions has a -1 formal charge in the central atom?

N I B S C
HO O I I F O O H O H




2) Which of the following molecules/ions has a +1 formal charge in the central atom?


O O P O O S O N N P S
F F F O




Topic 2: Electrophilicity & Nucleophilicity

Electrophile: Lewis acid, incomplete octet, cation, positive dipole
Nucleophile: Lewis base, neutral molecules w/ lone pairs, anion, negative dipole

1) In which of the following compounds is the hydrogen a nucleophile?

NH3 HCl KH HF H2O




2) In which of the following compounds is the central atom a Lewis acid?

PCl5 NH3 H4B- H2O H2N-




3) Use arrow-pushing to indicate the flow of electrons.


+ H O O + Cl
Cl H