(8) Which of the halogens has the largest atomic radius?
Atomic radius increases moving down a column. The halogens are the elements in the seventh column next to the noble gases. The halogen with the greatest atomic radius is then astatine.
(9) Which of the noble gases has the least first ionization energy?
The noble gases comprise the column on the right of the periodic table. First ionization energy decreases as atomic radius increases since there is more shielding of the attractive charge of the nucleus. The noble gas with the least first ionization energy is radon.
