Periodic Mole
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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

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Halogen

Group 17. One electron short of a noble-gas configuration — among the most reactive nonmetals on the table.

Worth knowing

  • Gain one electron to form −1 ; combine with metals to make salts (“halogen” = “salt-former”).
  • Reactivity decreases down the group: F > Cl > Br > I.
  • Fluorine is the most element on the table.

Examples

FClBrIAt

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 →