What is the difference between group and period?
A group is a vertical column (same valence electrons, similar properties); a period is a horizontal row (same number of shells).
A group is a vertical column (same valence electrons, similar properties); a period is a horizontal row (same number of shells). A reliable way to keep them apart is to focus on what each one is defined by, not just the similar-sounding words.
Key point
group vs period
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