Chapter 2: Q2.2-4CC. (page 36)
In Figure 2.7, if two or more elements are in the same row, what do they have in common? If two or more elements are in the same column, what do they have in common?
Short Answer
The number of electron shells in each element is the same if two or more two elements belong to the same row.
When two or more two elements belong to the same column, their valence shells have the same amount of electrons and have chemical characteristics that are similar.