Question

In the following, the element with the highest ionization energy is: (a) \([\mathrm{Ne}] 3 \mathrm{~s}^{2} 3 \mathrm{p}^{1}\) (b) \([\mathrm{Ne}] 3 \mathrm{~s}^{2} 3 \mathrm{p}^{3}\) (c) \([\mathrm{Ne}] 3 \mathrm{~s}^{2} 3 \mathrm{p}^{2}\) (d) \([\mathrm{Ne}] 3 \mathrm{~s}^{2} 3 \mathrm{p}^{4}\)

Short answer

Option (b) \( 3\mathrm{~s}^2 3\mathrm{p}^3 \) has the highest ionization energy.

Step-by-step solution

Review Definition of Ionization Energy

Ionization energy is the energy required to remove an electron from an atom in the gaseous state. It generally increases across a period in the periodic table and decreases down a group.

Identify Electron Configurations

Review the given electron configurations. Each configuration corresponds to an element in the same period (3rd) since they start with \( [\mathrm{Ne}] \), indicating they have the electron configuration of neon plus additional electrons in the third shell.

Determine Number of Unpaired Electrons

Compare the number of unpaired electrons for each element, as the ionization energy is typically higher when the electron configuration is more stable. The configurations are: - (a) \( 3\mathrm{~s}^2 3\mathrm{p}^1 \): 1 unpaired electron.- (b) \( 3\mathrm{~s}^2 3\mathrm{p}^3 \): 3 unpaired electrons.- (c) \( 3\mathrm{~s}^2 3\mathrm{p}^2 \): 2 unpaired electrons.- (d) \( 3\mathrm{~s}^2 3\mathrm{p}^4 \): 2 unpaired electrons.

Evaluate Electron Configuration Stability

Electrons in a half-filled shell (like the \( 3\mathrm{p}^3 \) configuration) create increased stability due to symmetrical distribution. This is seen in the highest ionization energy for configurations that are half-filled or more stable.

Conclude with Highest Ionization Energy

Based on stability and electron configuration, \( 3\mathrm{p}^3 \) in option (b) is a half-filled configuration, which is typically very stable. Hence, it has the highest ionization energy among the options.

Key concepts

Electron Configuration

Electron configuration is how electrons are distributed among the different atomic orbitals. Each orbital can hold a limited number of electrons, and they fill according to specific rules. When talking about electron configuration, we often begin with the nearest noble gas, in this case, Neon, because it gives us a useful short form. For example, the notation \( [\mathrm{Ne}] 3s^2 3p^1 \) means the element has the electron configuration of Neon plus additional electrons filling the 3s and 3p orbitals. Understanding this helps predict chemical behavior and interactions, as well as physical properties like ionization energy.

Periodic Table Trends

The periodic table is not just a list of elements; it organizes them to show periodic trends. One key trend is ionization energy, which tends to increase as you move from left to right across a period. This happens because the added electrons are in the same energy level, but the increasing nuclear charge means electrons are pulled closer and held more tightly. As a result, more energy is required to remove an electron. Understanding periodic trends like ionization energy helps predict how different elements might react with each other.

Unpaired Electrons

Unpaired electrons are electrons that occupy orbitals singly rather than in pairs. They can significantly affect the ionization energy of an atom. For instance, in the electron configuration \( 3p^3 \), there are three unpaired electrons, creating stability because of this half-filled subshell. The more unpaired electrons in a configuration, typically, the higher the ionization energy because they contribute to an atom's magnetic properties and increase stability under certain configurations.

Stability of Electron Configurations

Electron configurations that are fully filled or half-filled tend to be more stable due to symmetry and electron pairing. This stability is crucial when considering ionization energy. For example, a half-filled \( 3p^3 \) subshell is more stable than partially filled configurations like \( 3p^1 \) or \( 3p^2 \). This stability results from the symmetrical distribution of electrons, reducing electron-electron repulsion. A stable configuration generally leads to a higher ionization energy since it requires more effort to disrupt this balance. Understanding stability alongside electron configurations helps predict which atoms are more resistant to losing electrons.