UCLA CHEM 20A: Chemical Structure
CHEM 20A opens UCLA's general chemistry sequence for chemistry, biochemistry, and physical-science majors, focusing on quantum theory, atomic and molecular structure, and bonding with more mathematical rigor than the 14-series. It's the physical-science counterpart to CHEM 14A.
Fennie is independent and not affiliated with UCLA. This is an unofficial study guide.
What makes it hard
The quantum mechanics is real (wavefunctions, orbitals, and the math behind them), and students expecting high school chemistry plus get hit with material that feels closer to physics. The smaller, major-focused cohort means the curve offers less shelter than the giant 14-series courses.
What you'll cover
- • Quantum theory and wave-particle duality
- • Atomic orbitals and electron configurations
- • Periodic trends
- • Covalent bonding and molecular orbital theory
- • Molecular geometry and intermolecular forces
The CHEM 20A study guide
How to study for UCLA CHEM 20A, step by step.
- 1
Tune up the math before the quarter
CHEM 20A's quantum treatment leans on logarithms, exponentials, and comfort with functions. A short pre-quarter math refresh removes the most common friction with the wavefunction material.
- 2
Touch the quantum concepts daily
Orbital and bonding intuition builds in layers that can't be crammed, and ten weeks gives no digestion time. Brief daily review of the conceptual material beats long weekend sessions.
- 3
Explain diagrams out loud
For every orbital diagram and MO ordering, practice explaining why it looks the way it does, to a study partner or an empty room. If the explanation stalls, you've found the gap before the exam does.
- 4
Make periodic trends and bonding rules automatic
Exams assume trends in radius, ionization energy, and electronegativity are instant recall. Drill them early so exam time goes to the genuinely hard quantum reasoning.
Today
Today's CHEM 20A plan
What a Fennie Daily Plan looks like for CHEM 20A. Yours is built from your own syllabus and adapts every day to your deadlines and progress.
First plan free, no card required. Fennie is independent and unaffiliated with your school.
FAQ
Is CHEM 20A harder than CHEM 14A?
It's more mathematically rigorous: the quantum and bonding treatment goes deeper, befitting chemistry and engineering majors. Whether it feels harder depends on your math comfort; students strong in math sometimes prefer 20A's approach.
Who takes CHEM 20A at UCLA?
Chemistry, biochemistry, chemical engineering, and other physical-science majors. Life-science and pre-med students take the 14-series instead. Confirm your major's required series before enrolling, since the sequences don't mix freely.
What should I review before CHEM 20A?
Algebra fluency and basic high school chemistry are assumed; comfort with logarithms and exponentials helps with the quantum material. The course teaches its physics from scratch but moves fast; a ten-week quarter leaves no review weeks.
More UCLA courses
CHEM 14A: Atomic and Molecular Structure, Equilibria, Acids, and Bases
CHEM 14A is the first course in UCLA's general chemistry series for life-science majors and the standard pre-med chemistry entry point. It covers quantum concepts, atomic structure, bonding, equilibrium, and acid-base chemistry on a ten-week clock.
CHEM 14B: Thermodynamics, Electrochemistry, Kinetics, and Organic Chemistry
CHEM 14B is the second course in UCLA's general chemistry series for life-science majors and pre-meds, covering chemical equilibria, thermochemistry and the laws of thermodynamics, electrochemistry, chemical kinetics, and an introduction to organic concepts. It follows CHEM 14A on a ten-week clock.
CHEM 14C: Structure of Organic Molecules
CHEM 14C is UCLA's organic chemistry course for life-science majors and pre-meds, covering resonance, stereochemistry, conjugation and aromaticity, and spectroscopy (NMR, IR, and mass spectrometry), with emphasis on biological applications. It follows CHEM 14B and is the pre-med organic gateway.