Which of the following elements is a diatomic molecule?

Appeared in: UPUMS Nsg.Officer-2024

Explanation

Hydrogen naturally exists as a molecule made of two atoms, denoted as H₂.
This occurs because a single hydrogen atom has one electron and needs two for a stable outer shell. By sharing electrons, two hydrogen atoms form a stable covalent bond.
Elements that exist as pairs in their natural state are called diatomic molecules. Other common examples include Nitrogen (N₂) and Oxygen (O₂).

Option A: Sulphur is a polyatomic element, most commonly existing in a stable ring structure of eight atoms (S₈).
Option B: Argon is a noble gas with a full outer electron shell, making it chemically inert. It exists as a single, uncombined atom (monatomic).
Option C: Helium is also a noble gas with a complete outer electron shell. It is very stable and exists as a single, monatomic atom.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Identification of diatomic molecules among common elements as background academic context rather than a clinical decision trigger.
Understanding basic chemistry, such as molecular structures, is foundational for grasping pharmacology (how drugs are formed and interact) and physiology (e.g., gas exchange involving O₂ and CO₂).
The concept of diatomic gases is directly relevant to respiratory physiology, as oxygen (O₂) is essential for cellular respiration and is transported in the blood.
What if the question was about gases used in healthcare? The answer might be Oxygen (O₂) or Nitrous Oxide (N₂O), both of which are diatomic or contain diatomic components, highlighting the importance of molecular structure in medical applications.

How to Approach the Question

First, define the key term 'diatomic molecule'. 'Di-' means two, so it refers to a molecule made of exactly two atoms.
Review the options and recall the basic chemical properties of each element.
Identify any noble gases among the options (Helium, Argon). Noble gases are known for being chemically inert and stable as single atoms (monatomic), so they can be eliminated.
Consider the remaining elements. Sulphur is known to form larger, more complex structures (polyatomic, like S₈).
Finally, evaluate Hydrogen. It is one of the seven common elements that exist as diatomic molecules in their natural state (H₂, N₂, O₂, F₂, Cl₂, Br₂, I₂). This makes it the correct choice.

Concept Tested & Keywords

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E6 Pathology- ROBBINS & COTRAN PATHOLOGIC BASIS OF DISEASE 10TH Ed p. 62-64

E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 1 (pp 26-370 of 370) p. 19-21

Practise the full UPUMS Nsg.Officer-2024

Attempt every question from this paper in a timed mock, then review the full solution for each one.