Chemistry / Unit 2 Chem 0285 worked example, 60 to 90 seconds
Named Families of the Periodic Table
The idea
Several periodic-table groups carry specific family names beyond their number, and identifying an element's family means matching its group to that name.
In practice
Group 1 elements, except hydrogen, are alkali metals; group 2 elements are alkaline earth metals; group 17 elements are halogens; group 18 elements are noble gases. Chlorine, in group 17, is therefore a halogen. Calcium, in group 2, is an alkaline earth metal. Sodium, in group 1, is an alkali metal. Krypton, in group 18, is a noble gas. Group 15 elements are pnictogens and group 16 elements are chalcogens, both less commonly named in everyday use than the first four families.
Where people slip
Hydrogen sits above group 1 on most tables but is not an alkali metal — its nonmetallic behavior places it outside that family despite its position.
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