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) \(\mathrm{He}, \mathrm{Ne}, \mathrm{Ar}, \mathrm{Kr}\)

Short answer

Option (d), \\(\mathrm{He}, \mathrm{Ne}, \mathrm{Ar}, \mathrm{Kr}\\), has the peaks of ionization energy.

Step-by-step solution

Understanding Ionization Energy

Ionization energy is the energy required to remove an electron from an atom in its gaseous state. It's typically higher for elements that have a full or nearly full electron shell, as they are more stable and less willing to lose an electron.

Identifying Elements with High Ionization Energy

Noble gases tend to have high ionization energies because they have full valence electron shells, making them stable and less likely to lose an electron.

Analyzing the Options

Option (d) - Elements \(\text{He, Ne, Ar, Kr}\) are noble gases, characterized by full electron shells and high ionization energies.Option (a) includes halogens, option (b) includes alkali metals, and option (c) is a mixed group. These generally have lower ionization energies than noble gases.

Selecting the Correct Option

From the analysis, the noble gases in option (d) - \(\text{He, Ne, Ar, Kr}\) - have the highest ionization energies among the given options.

Key concepts

Noble Gases

Noble gases are a group of elements found in Group 18 of the periodic table. They include elements like Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn). These elements are known for being extremely unreactive compared to other elements. The primary reason for this lack of reactivity is their full valence electron shell.

In their outermost electron shell, noble gases have a complete set of electrons, usually with 8 electrons, except for Helium, which has 2. This configuration makes them very stable, resisting the addition or removal of electrons.

This high stability also contributes to their high ionization energies. Ionization energy refers to the amount of energy required to remove an electron from an atom. Since noble gases have full electron shells, they require more energy to remove an electron compared to other gases.

In day-to-day applications, noble gases are used due to their inertness, like in lighting (neon lights) and providing inert atmospheres for processes that need to be conducted in non-reactive environments.

Periodic Table Trends

The periodic table is designed to showcase recurring trends in the properties of elements. One important trend is the variation in ionization energy across periods and groups.

As you move across a period from left to right, ionization energy generally increases. This increase is because of the addition of protons in the nucleus, which increases the attraction between the nucleus and the electrons.
At the same time, electrons are added to the same energy level, meaning they're no further from the nucleus but more tightly held. As you go down a group, ionization energy decreases. This decrease is due to electrons being added to higher energy levels, further from the nucleus, making them easier to remove.

Noble gases at the end of each period display the highest ionization energies within that period. Their full electron shells make them incredibly stable and resistant to losing an electron. Studying these trends helps in predicting the chemical behavior of elements.

For example, elements with high ionization energies, such as nonmetals, tend to gain electrons during reactions, whereas those with low ionization energies, like alkali metals, tend to lose electrons.

Electron Configuration

Electron configuration refers to the distribution of electrons in an atom's shells and subshells. It plays a crucial role in determining the chemical properties of an element.

Electrons in an atom are arranged according to the principles of quantum mechanics. The configuration follows the Aufbau principle, which states that electrons fill atomic orbitals of the lowest available energy levels before occupying higher ones.
The configuration is usually written as a sequence of numbers and letter codes that indicate energy levels and subshells, like 1s²2s²2p⁶ for Neon (Ne).

Noble gases are distinguished by their full outer electron shells. For instance, Neon has a complete second shell (2s²2p⁶), resulting in maximum stability. This complete electron configuration makes noble gases particularly stable and gives them their characteristic high ionization energy.

Understanding the electron configuration helps predict how an element is likely to react. Elements with nearly full or nearly empty shells tend to be more reactive, striving to achieve a stable configuration similar to that of noble gases.