Describe the trends in electron configuration in the periodic table by selecting the terms from the drop-down menus.

the number of valence electrons from the left to right across a period.
the number of valence electrons from the top to the bottom of a group.
electrons are added into the outermost in groups 1 and 2.
electrons are added in the outermost in groups 3 through 12.
electrons are added in the outermost in groups 13 through 18.