Do columns or rows in the periodic table have repeating patterns?

Do columns or rows in the periodic table have repeating patterns?

• A. Rows
• B. Columns
• C. Both
• D. Neither

Answer: (B)

The repeating patterns show up most clearly down a column because elements in the same column (group) share the same valence electron configuration. That similarity gives them very similar chemistry, so properties repeat as you move from one period to the next within the same column. For example, the alkali metals in one column are all highly reactive and form +1 ions, the halogens form -1 ions, and the noble gases are very inert. Across a row, properties change more gradually as you add electrons and fill new subshells, so the repetition isn’t as pronounced. So the recurring patterns occur by columns, not rows.

The repeating patterns show up most clearly down a column because elements in the same column (group) share the same valence electron configuration. That similarity gives them very similar chemistry, so properties repeat as you move from one period to the next within the same column. For example, the alkali metals in one column are all highly reactive and form +1 ions, the halogens form -1 ions, and the noble gases are very inert. Across a row, properties change more gradually as you add electrons and fill new subshells, so the repetition isn’t as pronounced. So the recurring patterns occur by columns, not rows.