Final answer:
Fluorine (F) and neon (Ne) have the same number of valence electrons, each with eight, as they are both in Group 18 of the periodic table. Lithium (Li) has one valence electron, being in Group 1, while argon (Ar) has eight valence electrons, like neon.
Step-by-step explanation:
The elements that have the same number of valence electrons are fluorine (F) and neon (Ne). Both of these elements are in Group 18 of the periodic table, known as the noble gases, which means they have eight valence electrons. This full valence shell gives them a uniqueness in terms of chemical reactivity. Unlike fluorine (which is very reactive), neon is inert. This disparity in reactivity is due to neon being a noble gas with a full outer electron shell, whereas fluorine seeks to gain one more electron to achieve a full shell.
Lithium (Li) and argon (Ar) do not share the same number of valence electrons. Lithium belongs to Group 1 and has only one valence electron, which is evident from its electron configuration [He]2s¹. In contrast, argon, another noble gas in Group 18, has a complete set of eight valence electrons, like neon.