Unit 01 · Atomic Structure & the Periodic Table
This unit builds from the inside of the atom outward: the three subatomic particles and what each contributes to mass and charge, how isotopes differ, how electrons fill orbitals, and how those configurations explain the patterns — atomic radius, ionization energy, electronegativity — that march across the periodic table. Mastery means you can read the table as a map of electron behavior, not a chart to memorize.
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Subatomic particles & atomic notation | Confuses protons, neutrons, and electrons or their charges. | Names the particles but stumbles reading mass number vs. atomic number. | Reads any isotope symbol fluently and states protons, neutrons, electrons, and charge. |
| Isotopes & average atomic mass | Thinks all atoms of an element are identical. | Defines isotopes but cannot weight a mass average. | Calculates average atomic mass from isotope abundances and explains why it is rarely a whole number. |
| Electron configuration & orbitals | Writes configurations as random letters and numbers. | Fills orbitals but violates Hund's rule or the Aufbau order. | Writes ground-state, noble-gas, and orbital-diagram configurations correctly, including exceptions like Cr and Cu. |
| Periodic trends | Cannot state whether a property rises or falls across a period. | Recalls a trend's direction but not its cause. | Predicts and ranks radius, ionization energy, and electronegativity using effective nuclear charge and shielding. |
| Lab technique (flame tests / spectra) | Skips or contaminates the flame-test loop. | Runs the test but misassigns colors to elements. | Performs clean flame tests, links emission colors to electron transitions, and identifies an unknown salt. |
| Integration (cross-domain) | Treats the science as isolated facts; makes no cross-domain connection. | Names a link to history, reading, or writing but cannot defend why it matters. | Connects the unit to its anchor across History · Reading · Writing (plus chosen electives) and defends why the connection matters. |
“Chlorine-37 still has 17 protons and 20 neutrons — the mass number changes, not the element, because the proton count is fixed. And chlorine sits to the right of silicon, so it’s smaller and pulls electrons harder. That’s a trend I can reason out, not a fact I memorized.”
“It has 17… protons? And the table goes by size, I think — the big ones are over on one side.”
You demonstrate this unit through flame-test and spectroscopy labs plus short oral checks where you reason from electron structure aloud — not a multiple-choice test. A criterion counts as mastered only when you can both run the technique and justify the atomic chemistry behind it. Mastery is demonstrated, not awarded.
A 5-page clipboard packet — unit overview, key terms, the mastery rubric, anchor examples, and a score sheet you can print and grade against.