Question

Which of the following species are isoelectronic: \(\mathrm{NH}_{4}^{+}, \mathrm{C}_{6} \mathrm{H}_{6}, \mathrm{CO}, \mathrm{CH}_{4}, \mathrm{~N}_{2}, \mathrm{~B}_{3} \mathrm{~N}_{3} \mathrm{H}_{6} ?\)

Short answer

The isoelectronic pairs are \(\mathrm{NH}_{4}^{+}\) with \(\mathrm{CH}_{4}\), and \(\mathrm{CO}\) with \(\mathrm{N}_{2}\).

Step-by-step solution

Understand Isoelectric Species

Isoelectric species are atoms, ions, or molecules that have the same number of electrons. To find which of the given species are isoelectronic, we need to count the total number of electrons in each species.

Count Electrons in Each Species

Let's find the total number of electrons for each species:- **\(\mathrm{NH}_{4}^{+}\):** \(\mathrm{N}\) has 7 electrons, and each \(\mathrm{H}\) has 1 electron. Total is \(7 + 4 = 11\). Since it has a \(+1\) charge, subtract 1 electron, resulting in 10 electrons. - **\(\mathrm{C}_{6} \mathrm{H}_{6}\):** \(\mathrm{C}\) has 6 electrons, \(\mathrm{H}\) has 1 electron. Total is \(6\times6 + 6\times1 = 42\) electrons.- **\(\mathrm{CO}\):** \(\mathrm{C}\) has 6 electrons, \(\mathrm{O}\) has 8 electrons. Total is \(6 + 8 = 14\) electrons.- **\(\mathrm{CH}_{4}\):** \(\mathrm{C}\) has 6 electrons, \(\mathrm{H}\) has 1 electron. Total is \(6 + 4 = 10\) electrons.- **\(\mathrm{N}_{2}\):** Each \(\mathrm{N}\) has 7 electrons. Total is \(7 + 7 = 14\) electrons.- **\(\mathrm{B}_{3} \mathrm{N}_{3} \mathrm{H}_{6}\):** \(\mathrm{B}\) has 5 electrons, \(\mathrm{N}\) has 7 electrons, \(\mathrm{H}\) has 1 electron. Total is \(3\times5 + 3\times7 + 6\times1 = 24\) electrons.

Identify Isoelectronic Species

Compare the electron counts. We find that:- \(\mathrm{NH}_{4}^{+}\) and \(\mathrm{CH}_{4}\) both have 10 electrons.- \(\mathrm{CO}\) and \(\mathrm{N}_{2}\) both have 14 electrons.Thus, these pairs are isoelectronic.

Key concepts

Electron Counting

Electron counting is a critical skill for identifying isoelectronic species. By determining the total number of electrons in different atoms, ions, or molecules, we can see if they match up. Finding connections helps us understand chemical properties better.

To count electrons, follow these simple steps:

• Identify the number of valence electrons for each element, using the periodic table as your guide.
• Add electrons based on the composition of the molecule or compound.
• Adjust for any charges by adding electrons for negative charges or subtracting for positive ones.

These steps help you understand how atoms or molecules might interact with others.

Atoms and Ions

Atoms are the fundamental units of matter, consisting of protons, neutrons, and electrons. Ions form when atoms gain or lose electrons, resulting in a charge. Understanding this helps us with electron counting, which is essential for identifying isoelectronic species.

Atoms and ions share this basic structure:

• Protons determine the atomic number and identity of an element.
• Neutrons provide stability, and together with protons form the nucleus.
• Electrons, which orbit the nucleus, are involved in chemical reactions and bonding.

Ions differ from neutral atoms mainly because of their unbalanced charge, but they can still share electron counts with other species.

Valence Electrons

Valence electrons are the outermost electrons of an atom and play key roles in chemical bonding and reactions. Knowing how to identify and count them is crucial for understanding molecular interactions.

Here's how valence electrons influence chemistry:

• They determine the reactivity and bonding ability of an element.
• Elements in the same group of the periodic table have similar valence electron configurations, affecting their chemistry.
• Counting valence electrons helps predict how an atom will bond with others, forming stable compounds.

Mastering this concept makes it easier to see patterns in chemical behavior, like identifying isoelectronic species.

Chemical Species

Chemical species refer to atoms, molecules, ions, or particles that participate in chemical reactions. Understanding them allows us to compare and predict reactivity, polarity, and other chemical properties.

Key points about chemical species:

• They can be neutral (like atoms or molecules) or charged (like ions).
• Isoelectronic species are a subset where species have the same number of electrons.
• Recognizing them helps in predicting similar properties or behaviors in different substances.

By understanding chemical species, students can better grasp complex ideas like isoelectronicity and its significance in chemistry.