Periodic Mole
Unlock · $59

Periodic Table

Tap any element to see how it bonds, where you meet it in the games, and the concept pages that explain it.

Alkali metal6
Alkaline earth metal6
Transition metal38
Post-transition metal11
Metalloid7
Nonmetal7
Halogen6
Noble gas7
Lanthanide15
Actinide15

Family legend

Family

Lanthanide

, period 6. The “rare earths” — chemically very similar to one another, hard to separate.

Worth knowing

  • All form +3 ; ionic radius shrinks across the series (the ).
  • Used in phosphors (Eu in red, Tb in green), neodymium magnets, and MRI contrast agents.
  • Despite the name, most lanthanides are more abundant in the crust than silver.

Examples

LaCeNdEuGd

Behind the name

The Periodic Table

Mendeleev's pattern that lets a chemist predict an unknown element from its neighbors. Read the lore →

The Mole

6.022 × 10²³ of anything. The counting unit that bridges atoms and grams. Read the lore →