Chemistry / Unit 2 Chem 0276 short lesson, about 20 seconds
Periods and Groups
Captions available
The idea
A period is a horizontal row of the periodic table; a group is a vertical column whose elements share similar chemical properties.
In practice
Sodium and potassium sit in the same group, group 1, though sodium is in period 3 and potassium is in period 4.
Where people slip
IUPAC's 1-through-18 group numbering has replaced the older Roman-numeral American labeling system still seen on some tables.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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