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Eleven properties - mass, category, block, period, group, phase, melting and boiling point, electronegativity and electron shells - lined up in one table.
11 properties - mass, category, block, period, group, phase now, melting and boiling point, electronegativity and electron shells - lined up in one table, and downloadable as a CSV. Every figure is free to read on each element's own page; the side-by-side table and the file you take away are the Premium part.
The periodic table, every element detail, all 118 reference pages, search, the phase slider, the molar-mass calculator, and favorites stay free forever.
Pick elements and their properties line up side by side: atomic number, atomic mass, category, block, period, group, the phase at the temperature you have set, melting and boiling point, electronegativity and the electron shell breakdown. Any value the source data does not publish is shown as not available rather than guessed.
The heaviest synthetic elements have been made only a few atoms at a time, so many of their bulk properties have never been measured. An unmeasured value is left blank rather than filled in with a plausible-looking number, and an element with no published boiling point is reported as an unknown phase above its melting point rather than assumed.
Compare two elements in the same period and electronegativity rises towards the right of the table. Compare two in the same group and the electron shell breakdown gains a shell each step down, which is why the outer electrons are held more loosely and electronegativity falls down a column.