Question

Which of the electronic configuration represents a noble gas? (a) \(1 s^{2}, 2 s^{2}, 2 p^{6}, 3 s^{2}, 3 p^{6}\) (b) \(1 \mathrm{~s}^{2}, 2 \mathrm{~s}^{2}, 2 \mathrm{p}^{6}, 3 \mathrm{~s}^{2}, 3 \mathrm{p}^{3}\) (c) \(1 \mathrm{~s}^{2}, 2 \mathrm{~s}^{2}, 2 \mathrm{p}^{6}, 3 \mathrm{~s}^{2}, 3 \mathrm{p}^{1}\) (d) \(1 s^{2}, 2 s^{2}, 2 p^{6}, 3 s^{2}, 3 p^{4}\)

Short answer

The electronic configuration (a) represents a noble gas.

Step-by-step solution

Understand the Electronic Configuration of Noble Gases

Noble gases have completely filled valence shells, resulting in a stable configuration. The electron configurations for noble gases end with a fully filled s and p subshell in their highest-energy level.

Analyze Each Option for Complete Valence Shell

Compare each given option to determine if it ends with a fully filled p subshell in its highest energy level. - (a) ends with \(3 p^6\), - (b) ends with \(3 p^3\), - (c) ends with \(3 p^1\), - (d) ends with \(3 p^4\).

Identify the Noble Gas Configuration

A noble gas configuration will have a fully filled s and p subshell in its outermost shell. Option (a), which ends with \(3 p^6\), matches this criterion indicating a noble gas configuration for argon.

Conclusion

Option (a) is the only configuration that represents a noble gas with its full \(s\) and \(p\) subshells in the third energy level, characteristic of argon.

Key concepts

Electron Configuration

Electron configuration is a system that shows the distribution of electrons in an atom's orbitals. Recognizing how electrons fit into these orbitals is crucial for determining the chemical properties of an element. Electrons inhabit shells and subshells in a specific order, beginning at the lowest energy shells. In electron configuration notation, numbers specify the energy level, letters illustrate the type of orbital, and superscripts indicate the number of electrons within that orbital. For instance, in the configuration \(1s^2\), '1' refers to the energy level, 's' is the type of orbital, and '2' shows that there are two electrons in that orbital.

• First, electrons fill the lowest energy levels, starting with the 1s orbital.
• After filling one energy level, electrons then move to the next higher available energy level.
• The filling follows the aufbau principle – orbitals are filled in order of increasing energy.

Understanding electron configurations helps predict an element's reactivity and location on the periodic table.

Valence Shell

The valence shell is the outermost shell of an atom's electron configuration. It plays a vital role since the electrons in this shell determine how an atom interacts with others, including forming bonds. These interactions often depend on achieving a stable electronic configuration similar to that of noble gases. Noble gases have complete valence shells, making them highly stable and generally unreactive. For other elements, reaching a full valence shell often involves gaining, losing, or sharing electrons to mimic this noble gas configuration. Atomic stability is often linked to the "octet rule," where atoms are more stable when they have eight electrons in their valence shell. This tendency explains many chemical reactions where atoms adjust their electrons to achieve a full valence shell.

• Noble gases naturally possess a full valence shell, contributing to their chemical inertness.
• Other elements strive to achieve a similar stable configuration by adjusting their valence electrons during chemical changes.

Periodic Table

The periodic table is an organized chart depicting all known elements arranged by increasing atomic number. This layout not only makes it easier to locate elements but also reveals various trends, including how these elements behave chemically. Grouping Elements While reading the periodic table, you'll notice that columns, known as groups, hold elements sharing similar properties, including electron configurations. For instance, elements in the same group often have the same number of electrons in their valence shell, which governs their chemical behavior. Periods Reflect Energy Levels The rows of the periodic table, called periods, show the filling of electron shells. As you go across a period, electrons fill the available subshells and essentially shape the element's properties. Noble Gases Noble gases are located in Group 18 and are significant due to their complete valence shell. Their electron configurations end in a filled p subshell, highlighting their unique stability compared to other elements.

• The arrangement offers insights into periodic trends like electronegativity, atomic size, and ionization energy.
• Understanding the periodic table is crucial in predicting element behavior during reactions, especially in achieving stable configurations.