The Table's Greatest Hits

The periodic table is still growing. A few milestones worth knowing:

• 1869 — Mendeleev publishes his table with gaps for undiscovered elements
• 1875-1886 — gallium, scandium, and germanium are found, all matching his predictions
• 1913 — Moseley reorders the table by atomic number instead of weight
• 1940s onward — scientists start making synthetic elements heavier than uranium
• 2016 — four new elements (113, 115, 117, 118) complete the seventh row

It may be the most important single document in science: a pattern that sorts 118 confirmed elements and predicts how they behave, with room to grow as physicists push further.