Question

The HD \(^{+}\) ion contains (1) 1 proton, 1 neutron, 1 electron (2) 2 protons, 1 neutron, 2 electrons (3) 2 protons, 1 neutron, 0 electron (4) 2 protons, 1 neutron, 1 electron

Short answer

Option (3): 2 protons, 1 neutron, 0 electron.

Step-by-step solution

Understand the HD+ Ion

The HD+ ion is a molecular ion consisting of one proton (H+) and one deuterium nucleus (D+). Deuterium is an isotope of hydrogen with one proton and one neutron.

Deuterium Composition Analysis

Deuterium (D) has 1 proton and 1 neutron. When deuterium loses an electron and becomes D+, it retains its proton and neutron but has no electrons.

Combine H+ and D+ Information

The HD+ ion consists of one proton from H+ and one D+ nucleus with one proton and one neutron. Thus, HD+ contains two protons in total (one from H and one from D) and one neutron from D.

Determine the Electron Count

Since both H+ and D+ ions are positively charged, they do not have electrons. Therefore, the HD+ ion has no electrons.

Choose the Correct Answer

Combine the information: HD+ contains 2 protons, 1 neutron, and 0 electrons. Therefore, the correct answer is Option (3).

Key concepts

Proton Count in Ions

Understanding the proton count in ions is essential for grasping atomic structure and ion composition.
Protons are positively charged particles found in the nucleus of an atom. The number of protons in the nucleus defines the element. For example, hydrogen with one proton is the simplest atom.
Positive ions, like H+ (hydrogen ion), result from losing electrons but retain their proton count. In the context of the HD+ ion:

• H+ has 1 proton.
• Deuterium (D) has 1 proton and 1 neutron. When it loses an electron, it becomes D+.

Combining these, HD+ contains in total:

• 1 proton from H+
• 1 proton from D+

Thus, the HD+ ion has 2 protons.

Neutron Count in Deuterium

To understand the HD+ ion, we need to analyze the neutron content, especially from deuterium (D). Deuterium is an isotope of hydrogen:

• Regular hydrogen has no neutrons, just 1 proton.
• Deuterium, however, has 1 proton and 1 neutron.

When deuterium loses its electron to form D+, it retains its neutron and proton.
Therefore:

• HD+ having D+ contributes 1 neutron to the ion.

Combining with the previously discussed proton count, this makes the HD+ ion with 2 protons and 1 neutron.

Electronic Configuration of Ions

Electronic configuration involves understanding the arrangement of electrons in atoms and ions.
Normally, neutral hydrogen (H) has 1 electron orbiting around its nucleus and so does deuterium. However, when these atoms ionize to form positive ions (H+ and D+):

• They lose their electrons and thus, carry a positive charge.

Specifically for HD+:

• The H+ ion has 0 electrons.
• The D+ ion also has 0 electrons.

Combining this information, the HD+ ion, consisting of H+ and D+, has no electrons.
Therefore, the total electron count in HD+ is zero, contributing to its positive charge.