For the question: what is an atom?
Here you get to handle it. Enlarge an atom to a football pitch and walk in, change the three kinds of particle, count the hands on each element, and fold one line into a table.
How many of the atoms once breathed out by Admiral Yi Sun-sin are in the breath you are taking now? And is it written on those atoms whose they were? Atoms have no memory →
Enlarge one atom to the size of a football pitch and the nucleus is a grain of rice at the centre. Pull the slider all the way to go in. The magnification is the true ratio.
Move closer ×1
Add and remove red protons, grey neutrons and blue electrons one at a time. Only one of the three changes the name.
The protons decide the name. But the electrons decide how it behaves. On to Board 4.
All three have one proton, so all three are hydrogen. Each has just one more neutron than the last, and so each is one unit heavier. Hence heavy hydrogen: deuterium. The fuel for fusion is the second and third of these.
The fuel for fusion is the second and third. The more neutrons, the more easily they fuse, and the more energy comes out when they do.
Every atom gives, takes or shares electrons to fill the empty places on its top floor. That number is its hands. Choose two and have them join hands. None may be left over and none may go short.
First
Second
Number of hands of the first twenty
1, 0, 1, 2, 3, 4, 3, 2, 1, 0. And again 1, 2, 3, 4, 3, 2, 1, 0. The number of hands repeats. Stand those with the same number of hands in a column and you have the columns of the periodic table: the groups. Lithium, sodium and potassium are in one column because all three have one hand, and that is why all three explode in water. Helium and neon are in one column because neither has any.
How many hands is decided by the electrons and the empty places on the top floor. How the empty places come about is on Board 6.
Board 5 · Fold one line and it becomes a table
Fold the line where the number of hands repeats and it becomes a table. First the twenty, then the fold.
The first twenty
H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca
The line above folds at the dotted marks into four rows. Once folded, the same places light up in the big table below.
One line, in order of number. So far it is just twenty symbols. See how far apart lithium, sodium and potassium are.
Why it folds at 2, 8, 8 of all places is shown on Board 6.
Tap a cell to open that element's place and properties.
Board 6 · Where the electrons sit
An atom is a block of flats. Each floor has units of rooms, and a room seats up to two electrons. Let them in one at a time and watch who sits where. When the eight front-door places of the top floor are full, the row of the periodic table changes. Tap a floor label to see why it has that many rooms; tap a full room and a third electron tries to get in.
The rooms form a square, so there are 1, 4, 9, 16, and each time the square grows by a layer it gains 1, 3, 5, 7. One spinning left and one spinning right to a room, two at most. So each floor holds 2, 8, 18, 32. The row lengths of the periodic table come in pairs — 8, 8, 18, 18 — because the front door of the floor above is taken first and the back rooms of the floor below are filled later.
The football pitch of Board 1 is this block of flats, and the empty places on the top floor are the hands of Board 4. A few elements (chromium, copper, lanthanum, actinium and others) break this order slightly.
Wherever the front door of the top floor fills, the row changes. Those are the rows of the periodic table. Go back to Board 5.
Board 7 · And the other ninety-eight
Twenty can be memorised. A hundred and eighteen cannot. But you can pass through them once. Over the 4 minutes 34 seconds of this song the table fills from top left to bottom right. It is not fully lit until the song ends. The song is in Korean.
When the chorus comes, the elements already lit move at 95.7 BPM, a tempo measured from the recording itself. Each section sweeps a different way — by number, by group, by period, and in the bridge from the centre of the table outwards.
Lyrics — the Korean original
The underlined lines are the element phrases; in them the symbols of the elements are sung as Korean syllables. Tap any line and the song jumps there. Where the chorus repeats phrases from earlier verses, no new elements are lit; the places already lit flicker as if being recalled. The timings of the spoken lines are approximate, divided between the phrases on either side, and may be half a beat out — the moments at which elements light use only exact, hand-marked values.
The twelve phrases — which block of the table each one is
It reads far more easily after you have tried it.
Unfamiliar words are in the glossary
Why Na and K? The symbols for sodium and potassium do not match their English names because the symbols come from Latin (natrium, kalium).
The song's phrases and the elements are matched only phrase by phrase. The lyrics are compressed to whatever is easiest to sing, so pairing one syllable with one element goes wrong in places. The light that runs along within a phrase is rhythm, not an exact correspondence.
Memorising and knowing are different things, so here is something to look at once the names are learned. When someone asks what an atom is, open this page. It starts with a football pitch and a grain of rice.