One lesson, taught three ways: watch and listen, read and write, then do it with your hands. When you're done, rate how long each one took and how much it helped, and you'll get a report on what works best for you, with and without a time limit.
Tip: keep a rough count of how long each part takes you. You'll need it in step 4.
Make sure your device's audio is turned on.
This is hydrogen.
Electrons settle into the lowest energy level that has room. Level 1 holds two electrons. Hydrogen has one electron and helium has two, so both fit in level 1. Lithium has three. Level 1 is already full, so the third electron goes to level 2, which is higher in energy and much farther from the nucleus.
An electron doesn't travel a fixed circle like a planet. Quantum mechanics tells us how likely it is to be found at each distance from the nucleus. That's called the radial probability, and it's what the colors in the animation and the curves above show. Darker color or a taller curve means the electron is more likely to be there.
The electrons in this lesson sit in s orbitals, which are perfectly round. The chance of finding the electron is the same in every direction, so its distance from the nucleus tells the whole story. That's why a flat, two-dimensional picture works here.
In lithium, a level-1 electron is most likely 20 pm from the nucleus, and 90% of the time it stays within 52 pm. The level-2 electron is most likely about 217 pm out. Its curve has a small inner pocket close to the nucleus, and it spends about 5% of its time there. That pocket overlaps level 1, which is the faint green in the animation and on the chart.
An electron with more energy can climb farther from the nucleus against its pull, so it spends most of its time farther out. Level 2 has more energy than level 1, which is why lithium's third electron sits so much farther away.
Answer in your own words, then press Check. Claude reads your answer and tells you whether you got the idea. Spelling doesn't count.
You'll make a small model that shows the idea from steps 1 and 2: more energy, farther from the center.
If your lid won't spin well on its knob, hold it flat and swirl it in small circles instead. It shows the same thing.
To keep circling, the marble needs a push toward the center. The faster it goes, the bigger that push has to be. The lid's wall gets steeper farther out, so the marble climbs until the slope pushes it in hard enough.
An electron works the same way in one respect: with more energy, it can climb farther from the nucleus against its pull.
Where the model stops matching: in the lid, faster means farther out. In a real atom, a level-2 electron actually moves slower than a level-1 electron, and it doesn't follow a track at all. The lid shows how energy relates to distance, not the path an electron takes.
−1 means it hurt your understanding, 0 means no effect, 5 means it helped a lot. Your total can't go below 0: you need some understanding before anything can take away from it.
Your whole understanding is 100%. Each style's share has two parts: what it taught you directly (from your answers in B), and how much it compounded, building on the other two. Slide or type each style's compounding. The more a style compounds, the bigger its share, and the direct parts shrink to make room while keeping the same proportions to each other.
"Short" depends on the task. A minute is a lot for 5 × 9 and almost nothing for an essay. So the levels are factors of a short amount: Short = 1×, Medium = 3×, Long = 9×. We start the short amount at your middle time from part A. You can change both numbers.
| Style | Time | Resource intensity | Help | Core | Compounding | Style value | Value per log-time |
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