How many groups and periods are there on the periodic table?
Quick Answer
The periodic table has 18 groups and 7 periods. Groups run vertically, and periods run horizontally.
The Full Story
The modern periodic table is arranged into 18 vertical columns called groups and 7 horizontal rows called periods. Elements in the same group often share similar chemical properties because they have similar outer electron configurations. For example, Group 1 contains the alkali metals, and Group 17 contains the halogens. The 7th period includes some of the heaviest known elements, including synthetic ones created in particle accelerators. This layout helps chemists predict how elements will behave, bond, and react.
Key Facts
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"Why does the periodic table have exactly 18 columns?"
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