Creating atoms

Atoms are plain Markdown. You write them in any note, in the Atomus editor or in any other editor that can open the .md files in your vault. Atomus reads the shape and picks the matching review UI. You don't pick a type from a menu.

There are six shapes. Pick whichever fits what you're capturing.

1. Question and Answer

The simplest atom. One line, two sides of ==.

Capital of France? == Paris

On review you see the front (Capital of France?). You try to recall the back. You rate yourself with one key.

2. Multi-line answer

When the back doesn't fit on one line, indent the follow-up lines. Everything indented under == stays together as the answer.

How does FSRS reschedule? ==
  - updates stability after each rating
  - grows the interval as stability rises
  - targets ~90% retention by default

Use this for definitions with bullets, short explanations, or anything with structure you want to keep visible on review.

3. Multiple choice

Put each option on its own line. (x) marks the correct answer, ( ) marks a wrong one. You can have as many options as you want and more than one correct answer.

Which is O(1) average lookup? ==
  (x) hash map
  ( ) sorted array
  ( ) linked list
  ( ) balanced BST

On review Atomus shows the options in a random order. You pick; Atomus grades.

4. List answer

Numbered list under ==. The whole list is the back.

Three laws of motion ==
  1. inertia
  2. F = ma
  3. equal and opposite reaction

Good for ordered steps, "name the three…" style prompts, or short enumerations where the order matters.

5. Cloze

Cloze atoms hide a word or phrase inside a sentence. No == needed. The sentence itself is the atom, and the {{...}} marks the gap.

Simple cloze

One gap, one atom. On review you see the sentence with the word blanked and type what's missing.

The {{mitochondria}} powers the cell.

Cloze with distractors

Separate options with |. The first is the correct answer, everything after is a wrong option. On review you pick instead of typing.

The {{mitochondria|nucleus|ribosome|chloroplast}} powers the cell.

This is often faster to write than a full multiple-choice block when the question is "which word fits here".

6. Deadlines

A deadline isn't an atom. It's a task that wraps atoms, with a date. Write a checkbox, a title, @YYYY-MM-DD, and indent the atoms below it.

- [ ] Biochem midterm @2026-05-10
  Krebs cycle step 3 == isocitrate → α-ketoglutarate
  ATP yield of glycolysis == 2 net
  The {{mitochondria}} powers the cell.

Atomus sees the date and front-loads the atoms inside the task as the deadline approaches, pulling their reviews in so the material peaks on the day you need it. Check the box when the task is done and the atoms go back to their regular schedule.

Mixing types in one note

Nothing stops you from using several shapes in the same note. Atomus parses each match independently.

# Cell biology

The {{mitochondria}} powers the cell.

Which organelle packages proteins? ==
  (x) Golgi apparatus
  ( ) lysosome
  ( ) rough ER

Three domains of life ==
  1. Bacteria
  2. Archaea
  3. Eukarya

Three atoms, three different shapes, one note in your vault.

Where to write atoms

• The Atomus editor. Open any note, or your Inbox, and write the atom on its own line. It enters the review queue right away. See Capture.
• Any other editor. Open a .md file in your vault and add atoms. Atomus picks them up when the file changes. See What's inside.

If you'd rather write plain text and let AI draft the atoms, put the cursor on a line and press ⌥ A. See Extraction.