Answer
Group 16: oxygen with atomic number 8
Group 17: chlorine with atomic number 17
Work Step by Step
We are looking for an element in group 16, which begins with the element oxygen. We are also looking for the element in group 16 that is in row 2, which begins with the element lithium. Therefore, the group 16 element that is in row 2 of the periodic table is oxygen with atomic number 8.
We are looking for an element in group 17, which begins with the element fluorine. We are also looking for the element in group 17 that is in row 3, which begins with the element sodium. Therefore, the group 17 element that is in row 3 of the periodic table is chlorine with atomic number 17.