Identify an element with the lowest melting point?

WCL Staff Nurse - 2022

Biochemistry and Nutrition

Medium

Appeared in: WCL Staff Nurse - 2022

Explanation

Argon is a noble gas, and its atoms are held together in the solid state only by extremely weak interatomic forces known as London dispersion forces.
Due to these weak forces, very little thermal energy is required to overcome them and transition from a solid to a liquid state.
Consequently, Argon has a very low melting point of -189.3°C, which is the lowest among the given options.

Option B: Sulphur is a non-metallic solid. Its atoms form stable S₈ molecules, and these molecules are attracted to each other by van der Waals forces, which are significantly stronger than the forces in solid Argon, resulting in a higher melting point (115.2°C).
Option C: Titanium is a transition metal characterized by very strong metallic bonds between its atoms. These strong bonds require a large amount of energy to break, giving Titanium a very high melting point of 1668°C.
Option D: Zinc is a metal with strong metallic bonding. While its melting point (419.5°C) is lower than that of Titanium, the metallic bonds are substantially stronger than the intermolecular forces in Sulphur or Argon, making its melting point much higher.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Relationship between interatomic forces and physical properties (melting point) of elements as background academic context rather than a clinical decision trigger.
Understanding properties of elements like argon is relevant in modern medicine. Argon Plasma Coagulation (APC) is a non-contact thermal procedure used in endoscopy to control bleeding from lesions in the gastrointestinal tract.
Nurses may assist in procedures using APC and must be aware of the equipment, its function, and related safety precautions for both the patient and the medical team.
What if the question asked for the element with the highest melting point? Among the given options, the answer would be Titanium (1668°C) due to its very strong metallic bonding.

How to Approach the Question

First, identify the question type. This is a factual recall question from basic chemistry, testing knowledge of the periodic table and physical properties.
Next, analyze the options by classifying each element: Argon is a noble gas, Sulphur is a non-metal, and both Titanium and Zinc are metals.
Recall the general principle: the strength of the bonds or forces between atoms determines the melting point. Weak forces lead to low melting points, while strong bonds lead to high melting points.
Apply this principle: Noble gases (like Argon) have the weakest forces (London dispersion forces). Metals (like Titanium and Zinc) have strong metallic bonds. Non-metals that form molecules (like Sulphur) are in between.
Based on this hierarchy of forces (Noble Gas < Molecular Solid < Metal), conclude that Argon must have the lowest melting point.

Concept Tested & Keywords

Concept Tested: Relationship between interatomic forces and physical properties (melting point) of elements.
Stem keywords: element, lowest melting point
Lead-in keywords: Identify
Negative lead-in flag: false

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E6 Harper's Illustrated Biochemistry2023 (pp 26-793 of 813) p. 81-83