Question

Students are learning about the differences between elemental molecules and compounds in class. They create four models to represent elemental molecules and compounds. The four models are shown in the image.



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Salt is composed of one sodium atom and one chlorine atom. Which diagram MOST LIKELY represents salt molecules?


Model One


Model Two


Model Three


Model Four

Answer 1

Model Three.

Reason: NaCl is an ionic compound that forms a repeating lattice of alternating sodium and chloride ions, not discrete Na–Cl molecules. Model Three shows a regular, repeating arrangement of two different kinds of atoms, which best matches salt. The other models show either identical atoms or small discrete molecules.