Interactive Periodic Table of Elements

The periodic table of elements: how to read it

The periodic table, often called Mendeleev's table after the Russian chemist who published the first version in 1869, arranges the 118 known chemical elements by increasing atomic number, that is, by the number of protons in the nucleus. The 7 rows are periods: with one exception (palladium), the period number equals the number of occupied electron shells. The 18 columns are groups: in groups 1, 2 and 13 to 18 (except helium), elements in the same column have the same number of electrons in their outer shell, which is why they behave alike chemically (lithium, sodium and potassium all react violently with water). The two separate rows below the main table, the lanthanides and actinides, belong to periods 6 and 7; they sit underneath so the table stays easy to read. This tool uses colors to tell apart ten families: alkali metals, alkaline earth metals, transition metals, post-transition metals, metalloids, nonmetals, halogens, noble gases, lanthanides and actinides.

What each element card shows

Click a square and the card shows the atomic number, symbol, atomic mass in atomic mass units (the same number, in g/mol, is the molar mass you use in chemistry calculations), family, period, group and block (s, p, d or f). You also get the electron configuration, for example [Ar] 3d⁶ 4s² for iron, and the number of electrons in each shell, drawn as a diagram. Then come the state at 20 °C, melting and boiling points, density, electronegativity on the Pauling scale, van der Waals radius, first ionization energy, common oxidation states and year of discovery ("Antiquity" for elements known since ancient times, such as gold, iron and copper). When a value is unknown, as with the heaviest lab-made elements, the card shows a dash instead of making up a number.

Solid, liquid or gas: each element's state at any temperature

Choose "State at temperature": the slider runs from absolute zero (0 K, or −273.15 °C) to 6,000 K, and quick buttons jump to useful reference points (liquid nitrogen at −196 °C, ice melting at 0 °C, water boiling at 100 °C, 1,000 °C and 3,000 °C). You can switch between °C and K. Each square is colored by whether the element is solid, liquid or gas at standard atmospheric pressure, and a counter shows how many elements are in each state. You will see that at 20 °C only two measured elements are liquid (mercury and bromine), eleven are gases and all the others are solid, and that gallium and cesium melt just above room temperature. States are worked out from measured melting and boiling points. For the heaviest elements, of which only a few atoms have ever been made, no measurement exists: near room temperature the table shows the state predicted by theory (marked "(predicted)" on the card; copernicium, for example, would be a liquid), and further from 20 °C they appear hatched, with no data.

Printable periodic table: PDF or PNG, color or black and white

The print section creates a landscape A4 poster with all 118 elements. Pick color (one shade per family, with a legend) or black and white (three shades of gray for metals, metalloids and nonmetals, easy on ink). Choose whether to show element names and atomic masses, or ask for blank squares that keep only the atomic number: handy for a fill-in worksheet or a quiz in class. The PNG button downloads a high-resolution image; the Print button opens your browser's print dialog, where you just pick "Save as PDF" to get a periodic table PDF. Element names come in 15 languages, so switch the site language to get a poster in Spanish, French, German, Arabic, Chinese and ten more, a nice touch for language classes or bilingual students.

Learn the element symbols with the quiz

Knowing the symbols (Na for sodium, Fe for iron, Au for gold, Pb for lead) is the first step in middle school and high school chemistry. The quiz gives you rounds of 10 questions on the first 20, 36, 54 or all 118 elements, at your own pace. In "Symbol to name" and "Name to symbol" you pick from four options; in "Find it on the table" you get a name and click its square, which trains you to place each element in its family. Your score and streak show during the game, and your best result for each question type and element range is saved on your device. Tip: start with the first 20, then widen the range, and use the element card to understand why some symbols come from Latin (Na from natrium, K from kalium, Fe from ferrum, Ag from argentum, Pb from plumbum).