How to play
Choose what the game asks by, which elements it uses and how long the round is, then press Start round. The game names one element at a time and you pick its cell in the periodic table. The clock starts with the first element and stops when the last one is found. Every element of the round is asked exactly once, in random order.
A wrong pick counts as a mistake: the cell turns red and the line above the table tells you which element you actually chose. The same element stays until you find it. After three misses the correct cell is highlighted and you pick it to move on. At the end you see your time, your accuracy (correct picks divided by all picks), the number of mistakes and the elements to review. The best time is kept for each combination of mode, element set and round length; a round with a shown answer does not count.
Game modes
- By name: you get a name such as “Sodium”. Cells show symbols only, so you have to know that sodium is Na.
- By symbol: you get a symbol such as “Na”. Cells show atomic numbers only, so you have to know where the element sits.
- By atomic number: you get a number such as 11. Cells show symbols only.
In every mode the label that would give the answer away is left off the cells. There are five element sets: the first 20 elements (hydrogen to calcium), the 50 main-group elements (groups 1, 2 and 13–18), the 38 transition metals (groups 3–12), the 30 lanthanides and actinides, and all 118. With a set larger than 20 you can play 20 random elements or the whole set. The Study view prints number, symbol and name on every cell.
Controls
- Mouse or touch: click or tap a cell to pick it.
- Keyboard: the arrow keys move from cell to cell, Enter or Space picks, Esc stops the round. Down from the bottom of the main table goes to the lanthanide row and then to the actinide row; Up goes back.
- Phone: the table is wider than the screen, so it scrolls sideways inside its own frame. Swipe it or use the two arrow buttons above it; the text between them says which groups are in view. The question and the clock stay at the top.
How the periodic table is organised
The elements are listed in order of atomic number, the number of protons in the nucleus. The seven rows are periods; a new period begins each time electrons start to fill a new outer shell. The periods hold 2, 8, 8, 18, 18, 32 and 32 elements. The 18 columns are groups. In the main groups, elements in one column have the same number of outer electrons and therefore behave alike: group 1 holds the soft, reactive alkali metals, group 17 the halogens and group 18 the noble gases, which hardly react at all.
The table also falls into four blocks named after the type of orbital being filled: the s-block (groups 1 and 2, plus helium), the p-block (the rest of groups 13–18), the d-block (groups 3–12) and the f-block. Periods 6 and 7 are 32 elements long, so a full-width table would need 32 columns. To keep it at 18, the lanthanides (57–71) and actinides (89–103) are drawn as two rows underneath. They really belong between groups 2 and 4.
Some borders are conventions rather than facts. Chemists disagree on whether group 3 continues with lanthanum and actinium or with lutetium and lawrencium, so this table leaves two marked gaps and shows all 15 elements of each series below. There is no agreed list of metalloids, so that category is not used here. Group 12 is not always counted among the transition metals. Elements 109–118 have only been made a few atoms at a time, so their chemistry is mostly predicted.
Tips for learning the elements
- Open the Study view first and learn one small set at a time.
- Learn columns as families: lithium, sodium, potassium, rubidium, caesium and francium in group 1; fluorine, chlorine, bromine and iodine in group 17.
- Symbols that look unrelated to the English name usually come from Latin: Na (natrium), K (kalium), Fe (ferrum), Cu (cuprum), Ag (argentum), Au (aurum), Pb (plumbum), Sn (stannum) and Hg (hydrargyrum).
- Remember the noble gases by number: 2, 10, 18, 36, 54, 86 and 118. Each one ends a period, so the next number starts a new row in group 1.
- Play short rounds on several days rather than one long session, and replay the elements listed for review.
Frequently asked questions
How many elements are there?
118 have been confirmed, with atomic numbers 1 to 118, and they fill seven complete periods. The four newest names, nihonium, moscovium, tennessine and oganesson, were approved in 2016.
Why is it aluminium and caesium here?
The game uses the international spellings recommended by IUPAC: aluminium, caesium and sulfur. In American English the first two are usually written aluminum and cesium.
Who invented the periodic table?
Dmitri Mendeleev published the best-known early version in 1869. He ordered the elements by atomic weight and left gaps for elements not yet discovered. In 1913 Henry Moseley showed that atomic number is the correct ordering.
Is my best time sent anywhere?
No. Settings and best times are kept only in your browser’s local storage. Clearing the site data removes them.