Tukuk-OS🧪 Periodic Table Explorer
ℹ️ What this tool does & how it works
The whole table in one search box: name, symbol or atomic number, matched as you type. Weights are the IUPAC standard atomic weights rounded to four or five significant figures; for radioactive elements with no stable isotope the mass number of the longest-lived known isotope is shown, marked with a tilde. One hundred eighteen rows, no account, nothing fetched — the data is part of the page.
What the numbers actually mean
The atomic weight is not the proton count — it is the average mass of the element as found in nature, weighted across its isotopes, which is why chlorine is 35.45 and not 35: a third of natural chlorine is the isotope with 17 neutrons and two thirds carry 19. The families on this page are the column groups of the standard table; the lanthanides and actinides are listed in place by number rather than in the two floating rows, which is the honest way for a search box even if it breaks the printed habit.