Problem 109 - A Complete Resource Book in Chemistry for JEE Main

Question

The elements which occupy the peaks of ionization energy curve are (a) \(\mathrm{Cl}, \mathrm{Br}, \mathrm{I}, \mathrm{F}\) (b) \(\mathrm{Na}, \mathrm{K}, \mathrm{Rb}, \mathrm{Cs}\) (c) \(\mathrm{Na}, \mathrm{Mg}, \mathrm{Cl}, \mathrm{I}\) (d) \(\mathrm{He}, \mathrm{Ne}, \mathrm{Ar}, \mathrm{Kr}\)

Step-by-Step Solution

Answer

The elements with peaks of ionization energy are Che, Ne, Ar, KrE (option d).

Step 1: Understanding Ionization Energy

Ionization energy is the amount of energy required to remove an electron from an atom in its gaseous state. The elements with the highest ionization energies are typically the noble gases because they have complete outer electron shells and are very stable.

Step 2: Analyzing Given Options

To find the elements that occupy the peaks, we look for noble gases as they have high ionization energies. Analyze the options to identify which set of elements are noble gases.

Step 3: Identifying the Noble Gases

Option (d) lists Che, Ne, Ar, KrE. These elements are noble gases, characterized by their full valence electron shells, which leads to high ionization energies.

Step 4: Selecting the Correct Option

Since noble gases have peaks of ionization energy on the periodic table, the correct answer is option (d): Che, Ne, Ar, KrE.

Key Concepts

Noble Gases

Noble gases are found in Group 18 of the periodic table. These elements include Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn). They are known for their distinct lack of reactivity compared to other elements. This is due to their full valence electron shell, which makes them extremely stable and unlikely to participate in chemical reactions.
They have complete outer electron configurations, meaning they generally have eight electrons in their outer shell, except for Helium, which has two.

• Because of this full valence shell, noble gases have minimal tendency to gain or lose electrons, resulting in their inert nature.
• This quality also contributes to their use in lighting and high-tech applications where non-reactivity is crucial.

The high ionization energy is another defining factor of noble gases, making it difficult to remove an electron from these elements, further highlighting their stability.

Periodic Table Trends

Periodic table trends refer to predictable patterns observed within the periodic table's layout, primarily influenced by elements' atomic structure. These trends help us understand elements' properties, including their chemical reactivity and physical state.

• As we move from left to right across a period, ionization energy generally increases. This is because the atomic number increases, boosting the nuclear charge, which in turn draws electrons closer to the nucleus.
• Moving down a group, ionization energy typically decreases. This happens because the outer electrons are farther from the nucleus and are shielded by the inner electron layers, making it easier to remove them.

Within this framework, noble gases hold a special position with particularly high ionization energies due to their complete electron shells. Thus, by understanding these trends, we can better predict an element's behavior and properties across different groups and periods in the periodic table.

Ionization Energy Peaks

Ionization energy peaks occur notably in the noble gases, as these elements exhibit the highest ionization energies within their respective periods. This means that substantial energy is required to remove an electron from a noble gas atom.
The peaks in the ionization energy curve correspond to the stability provided by fully filled electron shells. Noble gases like Helium, Neon, Argon, and Krypton prominently feature these peaks.

• This high energy requirement underscores the reluctance of noble gases to lose electrons and form ions, reinforcing their inert nature.
• The trend of high ionization energy supports the practical and theoretical understanding of element reactivity, substantiating why these elements sit at the apex of ionization energy graphs.

Recognizing ionization energy peaks helps us reflect on the broader periodic table trends, offering insights into why some elements are more reactive than others, while noble gases remain near the apex, illustrating their unique electronic configuration and stability.