Question

Boron differs from the other elements of the group because it has (1) a different configuration in its penultimate shell. (2) a valence shell electronic configuration of \(s^{2} p^{1} .\) (3) \(10 d\) -electrons in third orbit. (4) high ionization potential.

Short answer

Option (4): high ionization potential.

Step-by-step solution

- Analyze Boron's Electronic Configuration

Boron has an atomic number of 5. Its electronic configuration is 1s² 2s² 2p¹.

- Examine Each Option

Look at the statements provided to see which one stands out as a unique feature of Boron.

- Check Configuration in Penultimate Shell

The penultimate shell for Boron is the 1s² shell. This configuration is similar to other light elements, eliminating option (1).

- Verify Valence Shell Configuration

Boron’s valence shell has the configuration 2s² 2p¹. This matches option (2), but this configuration is not unique to Boron within its group.

- Look for Presence of d-Electrons

Boron’s third orbit doesn’t have 10 d-electrons because its electronic configuration ends at the second orbit. This rules out option (3).

- Understand Ionization Potential

Boron has a high ionization potential compared to other elements in its group due to its smaller size and the stable configuration of 2s² 2p¹. This makes option (4) correct.

Key concepts

Valence Shell Configuration

The term 'valence shell configuration' refers to the arrangement of electrons in the outermost shell of an atom. For Boron, this configuration is crucial because it determines its chemical properties and how it bonds with other elements. Boron has an atomic number of 5, which means it has 5 electrons. Its electronic configuration is written as 1s² 2s² 2p¹.

The 'valence shell' is the second shell in Boron's case, containing the electrons in the 2s and 2p orbitals. The full configuration for the valence shell is 2s² 2p¹, indicating there are two electrons in the 2s orbital and one electron in the 2p orbital. This configuration is not unique to Boron in its group, but it is essential in understanding its reactivity and bonding behavior.

• It influences the type of bonds Boron can form.
• Plays a significant role in determining ionization energy.
• Affects Boron's chemical and physical properties.

Always remember, valence electrons are key players in chemical reactions because they are the most accessible and easily shared or transferred among atoms.

Ionization Potential

Ionization potential (or ionization energy) is a measure of the energy required to remove an electron from an atom or ion. For Boron, this is a significant concept due to its relatively high ionization potential for a group 13 element.

The first ionization energy of Boron is higher than that of aluminum, which is the next element in the group. This phenomenon can be attributed to several factors:

• Boron's smaller atomic size.
• The stable electronic configuration of Boron's valence shell (2s² 2p¹).

The higher ionization potential means:

• More energy is required to remove the first electron from Boron.
• Boron atoms are generally less reactive than those with lower ionization energies.

Having a higher ionization potential impacts Boron's chemical reactivity and its role in forming compounds. It also makes Boron less prone to lose electrons compared to other elements in its group.

Penultimate Shell

Understanding the 'penultimate shell' is essential when studying electronic configurations. The penultimate shell is the second-to-last shell of an atom, which in Boron's case is the first shell (1s²).

For Boron, the penultimate shell's configuration is simply 1s². Unlike the valence shell, the penultimate shell does not directly participate in bonding but still contributes to the stability of the atom.

Here's why it matters:

• It helps stabilize the atom by housing electrons close to the nucleus.
• Maintains the structure of the atom and contributes to overall electron shielding.

However, the configuration of Boron's penultimate shell (1s²) is not unique and is shared with several light elements like carbon and nitrogen. This similarity explains why the penultimate configuration isn’t a standout feature for Boron compared to its group members.

d-Electrons

The term 'd-electrons' refers to electrons in the d-orbital. These are not relevant for Boron as its electronic configuration ends at the 2p orbital.

To clarify, d-electrons are typically found in elements starting from the third period of the periodic table. In the third period, elements like Scandium begin to fill the d-orbitals.

• Boron does not have any electrons in the d-orbital.
• Its electron configuration is 1s² 2s² 2p¹, ending with p-orbitals.
• Thus, Boron cannot have 10 d-electrons in the third orbit.

The absence of d-electrons means Boron's reactivity and bonding characteristics are significantly different from those elements in later periods that do contain d-electrons. This distinction highlights the unique aspects of Boron’s chemical behavior compared to transition metals and other elements with d-electrons.