Build a diagram, defend its electrons, revise from evidence
Choose each bond and lone pair yourself, then compare independently computed electron and charge ledgers with your prediction.
Try a case before reading feedback. Predict the total available electrons and write your reasoning, experiment by constructing a graph, then record it to reveal checks. Use the ledger to understand a failure, apply the method to a changed ion and continue to a three-dimensional model. No earlier completion is required.
For a recap, inspect electron budgets and resonance. These original public construction tasks use standard species and rules; their answers are inspectable in this static app. “First retained” means the first proposal saved here, not proof of an unseen attempt. Saved explanation text and graph-check agreement do not establish independent mastery.
Build nitrite and an equivalent contributor
Build one connected nitrite contributor. Keep atom labels fixed. Explain your electron budget, local shells and formal charges; after recording, construct the other equivalent contributor by exchanging the roles of O1 and O2.
Compare two equivalent contributors of an ideal isolated nitrite ion. The two drawings do not mean the ion switches between two physical bond patterns.
Atom labels identify fixed nuclei. For nitrite use N0 as the center; ammonium has N0 bonded to each H; cyanide has C0 and N1. You may draw other links to inspect why a proposal fails this declared connectivity. The checker does not discover every possible isomer.
Neutral-atom valence counts: H 1, C 4, N 5, O 6. Subtract the signed ion charge from their sum for the electron budget. Hydrogen aims for a duet; these C, N and O cases use octets. Each bond order adds one shared pair. A multiple bond counts as one domain at either end, while each lone pair adds another domain.
Explain the electron total, local shells and formal charges. Predictions and diagrams save as drafts. Recording locks a copy of the first graph and its explanation before revealing diagnostics. Text presence is required; its scientific quality is not graded.
0/3 proposals recorded. No recorded feedback exposure for this case. The first and latest recorded proposals are retained; an intermediate second proposal is replaced by the third. Clearing the draft never clears retained history. After three records, the draft remains editable.
Continue from the diagram
Use the molecular geometry investigation to separate electron domains from molecular shape. Check a reviewer’s unfamiliar formula and ask them to assess the explanation, not merely the diagnostic results. This workbench covers only paired-electron H/C/N/O cases with specified nuclei and connectivity targets; it does not model radicals, expanded octets, orbital wavefunctions, energies or measured molecular dipoles.
Sources and model boundaries
The College Board AP Chemistry CED, effective Fall 2024, topics 2.5–2.7, supplies the construction, formal-charge and representation objectives. OpenStax Chemistry 2e, section 7.4 explains formal charge and nitrite resonance. Both were inspected 28 October 2026. Tasks, code and diagrams here are original; this is not an official AP assessment or a performed experiment.
Retain and move your work
Science backups include editable drafts and immutable first/latest graphs with their explanations. Older imports retain known first proposals and feedback exposure. When two histories differ, the existing first proposal is preserved and the incoming latest/draft is shown; a combined attempt count is a retained-history bound, not an audit log. Intermediate proposals are not all archived. Backups do not provide account sync or certify authorship.
Save a science backup or import one
Science work is stored locally in this browser, separately from mathematics and AI. It does not sync automatically. Use this science-only backup; this checkout's older all-subject export does not include science.
A legacy file is available only when the complete snapshot fits the 36 MB limit. For larger snapshots, prepare a complete file set below; never discard notebooks to make a smaller file.
Matching imported notebook drafts replace their current drafts. Omitted lessons and known first attempts remain. Export your current work first if you want to retain both drafts.
Complete file sets and course backups
A file set can hold more work than one science file. Keep its manifest and every part together. Each file is limited to 36 MB. This format needs this version of LearnAI or a compatible newer version; older versions can use only the legacy single-file backup above.
The set includes every saved science course and global continuation at this moment. Later edits need a new export. A conflicting tab exports its own visible work, which may differ from saved work in another tab.
0 file(s) selected. File order and filenames do not determine identity. Missing, changed or conflicting parts block the entire restore; no good part is applied by itself.
Science storage: loading. No account or remote computation is required.