Final answer:
The elements Se, Li, F, and Ge can be ordered by increasing atomic radius according to the periodic trend that size increases down a group and decreases across a period. This results in the order: F < Se < Ge < Li.
Step-by-step explanation:
To order the elements Se (selenium), Li (lithium), F (fluorine), and Ge (germanium) by atomic radius, we need to apply the periodic trend for atomic size. The atomic radius generally increases as we move down a group in the periodic table and decreases as we move across a period from left to right.
Considering these trends, lithium is in group 1 and is much larger than the other elements in question since it is the furthest left and has fewer electron shells compared to the others. Selenium and germanium are in the same group (group 14), but selenium is above germanium, so Ge has a larger radius than Se. Fluorine is in group 17, to the right of both Se and Ge in the periodic table, so it will have the smallest atomic radius of the group.
Therefore, when we arrange these elements by increasing atomic radius, we get: F < Se < Ge < Li.