Question

what are the columns and rows in the modern periodic ​

Answer 1

Answer:

the periods are showing the number of shells in the element

and groups shows the valency and valence electrons in the outermost

Answer 2

Answer:

The vertical columns in the modern periodic table are known as groups and the horizontal rows are known as periods. There are 7 periods and 18 groups in the modern periodic table.

Hope it helps :)