"Fluorine (F) would have a greater mass than lithium (Li) because it has more protons, neutrons, and electrons than lithium. Specifically, the atomic mass of fluorine is approximately 19 atomic mass units (amu), while the atomic mass of lithium is approximately 7 amu.
On the other hand, lithium would have a larger atomic radius than fluorine. This is because atomic radius tends to increase down a group (column) of the periodic table and decrease across a period (row). Lithium is located in Group 1 (the alkali metals) of the periodic table, while fluorine is located in Group 17 (the halogens). Elements in Group 1 have relatively large atomic radii due to their low effective nuclear charges and the shielding effect of their inner electrons.
In contrast, elements in Group 17 have relatively small atomic radii due to their high effective nuclear charges and the lack of shielding from their inner electrons. Therefore, since lithium is located in a group that has larger atomic radii, it would have a larger atomic radius than fluorine, which is located in a group with smaller atomic radii." (ChatGPT, 2023)