The Periodic Table
Unlock the deep logic connecting electron configurations, periodic trends, and chemical reactivity. Learn to predict elemental behavior, navigate transitional and relativistic oddities, and decode how the universe organizes matter.
Like Duolingo, but for The Periodic Table. Tomo turns the whole topic into a game you play five minutes a day, until it actually sticks.
79 levels across 8 sections, about 158 minutes end to end, roughly 32 days at five minutes a day. It moves through Reading the Table as a Predictive Engine, Main-Group Architecture: s- and p-Blocks, The Transition Metals: d-Block Complexity, Structural Anomalies and Diagonal Symmetries, The f-Block: Rare Earths and Actinides, Relativistic Physics and Superheavy Frontiers, Cosmic Origins and Technological Criticality, and Organizing Principles and Alternative Formats. It assumes you already know the basics.
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Key ideas in The Periodic Table
- Electrons enter the same valence shell without adding new shielding layers.
- Each added proton increases effective nuclear pull on every outer electron.
- Higher nuclear pull draws the entire electron cloud closer to the nucleus.
- Starting a new p-subshell requires less energy to strip than a full s-subshell.
- Boron dips below beryllium because its lone 2p electron is higher in energy.
- Oxygen dips below nitrogen because paired electrons in a p-orbital repel.
- Chlorine has a higher electron affinity than fluorine despite being below it.
- Fluorine's tiny 2p orbital forces incoming electrons into tight crowding.
- Why neutral atoms shrink from left to right across the same row despite adding mass
- Intense electron repulsion in small spaces reduces net energy released.
- Identifying where ionization energy dips reveal subshell transitions
- Metals hold outer electrons loosely and surrender them under mild conditions.
- Metallic character decreases steadily as you travel rightward across a period.
- Half-filled subshells provide an extra stability barrier against disturbance.
- Starting an entirely new subshell places an electron at a higher energy step.
- Forcing two electrons into one orbital creates mutual repulsion that aids loss.
You've tried the other tabs
Thirty open tabs. Four facts you actually kept.
You watched. You nodded. By Sunday it was gone.
One answer, then back to scrolling.
Eight weeks. You meant to finish. You didn't.
Tomo gives The Periodic Table the Duolingo treatment: levels, streaks, and quick quizzes that test what you just learned. That game loop is what the tabs above never had, so it's the one you actually finish.
Here's what playing it feels like
A real question from this course. Take your best guess.
As you move one step right across a period, what happens to the pull felt by outer electrons?
Get it right to open this lesson and 78 more in the app.
Where The Periodic Table takes you
- 1
Reading the Table as a Predictive Engine
- Predicting Reactivity from Core Periodic Trends
- Calculating Effective Nuclear Charge and Screening
- Electronegativity Scales and Bond Character Mapping
- 2
Main-Group Architecture: s- and p-Blocks
- Group 1 and 2 Dynamics: Solvation and Lattice Energy
- The Metalloid Frontier and Band Theory Transitions
- The Inert Pair Effect and Variable Main-Group Valency
- 3
The Transition Metals: d-Block Complexity
- d-Orbital Geometries and Crystal Field Splitting
- Variable Oxidation States and Redox Catalytic Cycles
- The Lanthanide Contraction and Heavy Metal Twins
- 4
Structural Anomalies and Diagonal Symmetries
- Diagonal Relationships and Charge Density Parallels
- Second-Row Exceptionalism in Period 2 Elements
- High-Pressure Transformation of Periodic Properties
- 5
The f-Block: Rare Earths and Actinides
- 4f vs 5f Orbital Behavior: Lanthanides vs Actinides
- Actinide Radiochemistry and the Nuclear Fuel Cycle
- 6
Relativistic Physics and Superheavy Frontiers
- Relativistic Quantum Effects in Heavy Atoms
- Superheavy Synthesis and the Island of Stability
- 7
Cosmic Origins and Technological Criticality
- Geochemical Differentiation and Goldschmidt's Rules
- Critical Elements and Technological Substitutability
- Stellar Nucleosynthesis and Cosmic Element Distribution
- 8
Organizing Principles and Alternative Formats
- Alternative Periodic Frameworks and Dimensional Models
8 sections · 20 units · 79 levels. Built to play, not to enroll.
You pick the voice
The Periodic Table is taught in the The Professor style: clear, structured, thorough. Want a different feel? In the app you can spin up the same topic in any of Tomo's teaching styles. Same facts, totally different vibe.
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