Question

Noble gases do not react with other elements because (a) the size is completely paired up and has stable electrons shells (b) the size of their atoms is very small (c) they are found in abundance (d) they are monoatomic

Short answer

(a) the size is completely paired up and has stable electron shells.

Step-by-step solution

Understanding the Question

We are asked to determine why noble gases do not react with other elements. The question provides multiple-choice options, so we need to select the most accurate one that explains the chemical inertness of noble gases.

Analyzing Each Option

Let's analyze each option: - **Option (a)**: The size is completely paired up and has stable electron shells. This implies that their electron shells are full, which is why they don't tend to form bonds. - **Option (b)**: The size of their atoms is very small. While noble gases do have small atomic sizes compared to many elements, this is not why they are unreactive. - **Option (c)**: They are found in abundance. Abundance does not affect chemical reactivity. - **Option (d)**: They are monoatomic. While noble gases exist as single atoms, this is a result of their unreactivity, not the cause.

Selecting the Best Option

The key reason noble gases are unreactive is due to their electron configurations. Option (a) indicates that the noble gases have stable electron shells due to paired electrons, which prevents them from forming bonds easily. This option best explains their lack of reactivity.

Key concepts

Chemical Inertness

Noble gases are renowned for their chemical inertness, meaning they generally do not react with other elements. This unique characteristic is primarily due to their perfect completion of outer electron shells. These gases, which include helium, neon, argon, krypton, xenon, and radon, display minimal tendencies to engage in chemical reactions. Their lack of reactivity is linked to their stability, as having a full valence shell provides minimal incentive to form new bonds. In the periodic table, noble gases are located in the far-right column, emphasizing their unique position and role in chemical processes.
Noble gases's chemical inertness is essential for practical applications. For example, because they do not react easily, they are used in environments where chemical stability is crucial, such as in lighting, welding, and elements shielding sensitive equipment from reactive substances.

Stable Electron Configuration

The stability of noble gases stems from their complete electron configurations. An atom is most stable when its outer orbit of electrons is full. For most noble gases, this means having eight electrons in their outer shell, known as an octet, except for helium, which is stable with just two electrons.
A stable electron configuration minimizes the energy of an atom, making it less likely to engage in reactions. This concept is frequently discussed in the context of the "octet rule," which gives insight into the unreactive nature of these elements. Because they naturally achieve their most stable form, noble gases do not need to gain, lose, or share electrons, thus rare reacting to form new compounds.

Atomic Size

Though the atomic size of noble gases may not directly contribute to their chemical inertness, it is still a noteworthy characteristic. Generally, atomic size refers to the distance between the nucleus of an atom and its outermost electrons.
In the noble gas family, helium is the smallest while radon is the largest. The trend across the noble gases is an increase in atomic size as you move down the group in the periodic table. Despite this varying size, the unique electron configurations remain the driving force behind their inert nature, rather than the physical size itself.

Monoatomic Gases

Noble gases are special because they exist as monoatomic gases, meaning they are found in nature as single, unbonded atoms rather than molecules. This aspect is both a reflection of a consequence of their chemical inertness. Since they do not form bonds, they do not form molecules, remaining as individual atoms.
This feature contributes to their low-density properties and makes them very distinct among other elements in the periodic table. Unlike diatomic or polyatomic gases, the energy barrier for noble gases to form bonds is much higher, reinforcing their presence as monoatomic entities in the atmosphere.