Periodic Table

How to use

Click any element and its details appear directly above the table — atomic mass, electron configuration, melting and boiling points, density, who discovered it and when, who named it, and a short description. Type in the search box to dim everything that does not match; it searches names, symbols and atomic numbers, so "79", "au" and "gold" all find the same square.

Colour by repaints the table. Category gives the familiar colouring; the numeric properties give a heatmap, so you can watch electronegativity climb toward fluorine, or density spike around osmium, as a picture instead of a list of numbers.

Compact view

On a phone the table scrolls sideways, because eighteen readable columns do not fit on a narrow screen. Compact view drops the atomic number and the element name, leaving just the symbol, which fits the whole table on one screen with no sideways scrolling — useful when you want the shape of the table rather than the labels. The squares get small enough to be fiddly to tap, so it stays optional; the search box finds any element by name, symbol or number either way. Your choice is remembered on this device.

The temperature view

Choose phase at temperature and a slider appears. Drag it and every element is recoloured by whether it is solid, liquid or gas at that temperature, using its real melting and boiling points. Room temperature shows the two elements that are liquid there — mercury and bromine — and pushing the slider up walks the table through melting in roughly the order the periods do it. Elements with no measured melting or boiling point, which is most of the synthetic ones past 100, are greyed out rather than guessed at.

Discovery dates

Each element shows the discovery year and the person or group credited with it, taken together from the same source so the two always agree. Credit is genuinely contested for a fair number of elements — oxygen carries two names and two years because Sendivogius and Scheele both got there before Priestley published, and hydrogen is credited to Cavendish in 1766 even though Boyle had produced the gas in 1671 without realising what it was.

Fourteen elements were in use before anyone was recording who found what. Those show known since and a period rather than a year — gold back to around 40,000 BC, copper to 9000 BC, iron and silver before 5000 BC. The people credited are regions and cultures, not individuals, because that is honestly as precise as the record gets.

About the numbers

Atomic masses are the conventional single values you would use in a calculation. IUPAC actually publishes an interval rather than one number for around a dozen elements — hydrogen and carbon among them — because the isotopic mix genuinely varies depending on where the sample came from. For homework the conventional value is the one you want; for isotope work, check the IUPAC table itself.

The table covers the 118 confirmed elements, ending at oganesson. Element 119 appears in some datasets but has never been synthesised, so it is not here.