How does the reactivity of neon (atomic number 10, period 2, group 18) differ from that of sodium (atomic number 11, period 3, group 1)? Explain your reasoning based on the properties of neon and sodium that you can infer based on their atomic numbers, periods, and groups.(4 points)

Answer 1

Neon (Ne) and sodium (Na) exhibit significantly different reactivities due to their positions in the periodic table, which determines their atomic structure and electronic configurations.

1. Group Classification:

   • Sodium (Na) is in Group 1 of the periodic table, known as the alkali metals. Alkali metals have one electron in their outermost shell (the valence shell), making them highly reactive. Sodium readily loses this electron to achieve a more stable electronic configuration, similar to that of noble gases.
   • Neon (Ne), on the other hand, is in Group 18, which consists of the noble gases. Noble gases have full outer electron shells (eight electrons in the case of neon), rendering them stable and largely unreactive. Neon does not tend to gain or lose electrons under normal conditions.

2. Atomic Structure:

   • Sodium has an atomic number of 11, meaning it has 11 protons and typically 11 electrons. Its electron configuration is 1s² 2s² 2p⁶ 3s¹, with a single electron in the third energy level (shell). This configuration makes sodium eager to lose that single electron and form positive ions (Na⁺), which accounts for its high reactivity.
   • Neon has an atomic number of 10, with an electron configuration of 1s² 2s² 2p⁶, signifying a completely filled outer shell. Having a complete valence shell gives neon a stable configuration, leading to very low reactivity and a lack of tendencies to form bonds with other elements.

3. Chemical Behavior:

   • Given its high reactivity, sodium reacts vigorously with water and halogens, forming compounds readily. The reactivity of alkali metals like sodium is characterized by their ability to lose electrons easily.
   • In contrast, neon does not generally participate in chemical reactions. Its stability means it does not form bonds with other elements and remains monoatomic in its gaseous form.

4. Reasoning Summary:

   • The fundamental difference in reactivity between neon and sodium arises from their electronic configurations and group classifications. Sodium, as an alkali metal, is designed to react to achieve stability by losing an electron, while neon, as a noble gas, possesses an already stable electron arrangement and thus does not react at all under normal conditions.

In summary, sodium is reactive due to its single valence electron that it readily loses, while neon's full outer electron shell makes it extremely stable and largely inert.