Problem 106 - A Complete Resource Book in Chemistry for JEE Main

Question

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

Step-by-Step Solution

Answer

(a) completely paired up electrons lead to stable electronic configuration.

Step 1: Understanding the Question

The question asks why noble gases do not react with other elements. To answer this, consider the characteristics that define noble gases, focusing on their electronic configuration.

Step 2: Identify Key Characteristics of Noble Gases

Noble gases have a full outer electron shell, meaning their valence shells are completely filled. This makes them stable and largely unreactive as they have a low tendency to gain or lose electrons.

Step 3: Evaluate the Options

- Option (a): "completely paired up electrons lead to stable electronic configuration" aligns with the fact that a full outer electron shell leads to stability. - Option (b): Size is not a primary reason for the inertness of noble gases. - Option (c): Being found in abundance does not relate to chemical reactivity. - Option (d): Being monoatomic is a result, not a cause of their stability.

Step 4: Choosing the Correct Option

Based on the evaluation, option (a) "completely paired up electrons lead to stable electronic configuration" accurately explains why noble gases do not typically react. Full electron shells confer stability and inert characteristics.

Key Concepts

Stable Electronic Configuration

Noble gases are well-known for having a stable electronic configuration. But what does this mean? In simple terms, a stable electronic configuration refers to the state where an atom's electrons are arranged in the most balanced and non-reactive manner possible. For noble gases, this stability is achieved by having a complete set of electrons in their outer shell.

When an atom has a stable electronic configuration, it doesn't have a desire to gain or lose electrons. This lack of electron exchange is what makes noble gases such as helium, neon, and argon so content with their existing state. They do not engage in reactions to form compounds because their electron arrangement is already ideal.
- A complete set of valence electrons (outer shell full)
- No need to lose or gain electrons - Results in low reactivity

This concept of stability through complete electron pairing is crucial in understanding why noble gases are largely unreactive in nature.

Full Outer Electron Shell

The term 'full outer electron shell' describes the situation where the outermost layer of an atom's electrons is completely occupied. This configuration is typically achieved when the outer shell has two electrons for helium or eight electrons for the other noble gases.

This full outer shell scenario can be compared to filling a jar fully so nothing more can be added without overflowing. Similarly, in a noble gas, having a full outer shell means there is no sp ace for additional electrons unless considerable energy is applied, making it resistant to change.

• Helium: 2 electrons
• Neon through Xenon: 8 electrons

A full outer shell results in an atom having less potential energy state. It is happy and settled, needing no additional electrons to gain stability. This complete filling of their outermost shell is an important reason why noble gases stand out as non-reactive elements in the periodic table.

Chemical Reactivity

Chemical reactivity refers to the propensity of a substance to engage in chemical reactions, either gaining or losing electrons to form bonds. The noble gases are at the far-right side of the periodic table and are famously known for their lack of chemical reactivity.

Their full outer electron shells are the primary reason behind this. Unlike other elements that actively seek to achieve a stable electronic configuration by altering their electron count through reactions, noble gases are already in their most stable form. They experience little to no urge to change their electron arrangement.
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• Inherent stability due to full shells
• Little tendency to form compounds
• Occupy last column of the periodic table, marking their unique non-reactive nature

Because of these full outer shells, noble gases have very limited interaction with other elements. This plays a massive role in maintaining their largely inert nature.