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⚛️AP CHEMISTRY STUDY GUIDE
Unit 1: Atomic Structure and Properties
Review moles, mass spectra, electron configurations, photoelectron spectra, and periodic trends for AP Chemistry Unit 1.
8 key ideas8 flashcards5 practice questions
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Read each peak as evidence about electrons.
relative electron count
held closer to the nucleus
Key ideas to know
Start with the relationships between ideas. Then close the notes and explain each one from memory.
- 01
A mole connects a measurable sample to a count of particles.
- 02
Mass spectra distinguish isotopes by mass-to-charge ratio and relative abundance.
- 03
Average atomic mass is a weighted mean of naturally occurring isotope masses.
- 04
Electron configurations describe electron occupancy in atomic orbitals.
- 05
Photoelectron spectra report electron binding energies and relative electron counts.
- 06
Coulombic attraction grows with greater charge and shorter distance.
- 07
Effective nuclear charge generally rises from left to right across a period.
- 08
Atomic radius generally decreases across a period and increases down a group.
PART OF THE AP CHEMISTRY GUIDE
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Open the full AP Chemistry guide →Two ideas worth correcting now
NOT QUITE
→Average atomic mass is the mass of the most common isotope
USE THIS INSTEAD
It is a weighted mean across naturally occurring isotopes.
NOT QUITE
→Electrons orbit the nucleus in fixed circular paths
USE THIS INSTEAD
Atomic orbitals describe probability distributions, not classical circular paths.
Flashcards
Answer before opening each card. The effort to retrieve is part of the learning.
1How many particles are in one mole?Show answer ＋
Approximately 6.022 × 10²³ representative particles.
2How is average atomic mass calculated?Show answer ＋
Multiply each isotope mass by its fractional abundance, then add the products.
3What does a taller peak in a mass spectrum usually indicate?Show answer ＋
A greater relative abundance of that isotope or fragment.
4What does a photoelectron spectrum peak area represent?Show answer ＋
The relative number of electrons with that binding energy.
5Which electrons are removed first during ionization?Show answer ＋
Electrons with the lowest binding energy, usually the outermost electrons.
6Why does atomic radius decrease across a period?Show answer ＋
Nuclear charge rises while added electrons remain in the same principal shell.
7What is shielding?Show answer ＋
Reduction of nuclear attraction on outer electrons due to inner electrons.
8Why is a cation smaller than its neutral atom?Show answer ＋
Electron loss reduces repulsion and may remove the outermost occupied shell.
Explain it in your own words
Use the answer as a check after you have written or spoken your response.
01A mass spectrum has isotope peaks at 35 and 37 with a three-to-one abundance ratio. What average mass is expected?
About 35.5 atomic mass units because the lighter isotope contributes three times as much.
02How can photoelectron spectra distinguish two elements in the same period?
Peak position and area indicate electron binding energies and counts, which differ with nuclear charge and configuration.
03Why does first ionization energy generally rise across a period?
Stronger attraction between the nucleus and valence electrons makes electron removal require more energy.
04Why can an electron configuration predict chemical behavior?
Valence electron arrangement affects bonding, ion formation, and recurring periodic patterns.
05How do distance and charge affect electrostatic attraction?
Greater charge increases attraction, while greater distance reduces it according to Coulomb's law.
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