Which statement best defines the term 'crystalline' when used to describe a solid?

• A. A crystalline solid is always electrically conductive due to free-moving electrons.
• B. A crystalline solid can only be formed from metals.
• C. A crystalline solid has atoms, ions, or molecules arranged in a highly ordered, repeating three-dimensional pattern.
• D. A crystalline solid is composed of particles that are randomly distributed without any long-range order.

Answer: (C)

Verified step by step guidance

1. Understand that the term 'crystalline' refers to the internal structure of a solid, specifically how its particles are arranged.
2. Recall that in a crystalline solid, atoms, ions, or molecules are organized in a highly ordered and repeating three-dimensional pattern, which is called a crystal lattice.
3. Recognize that this ordered arrangement distinguishes crystalline solids from amorphous solids, where particles lack long-range order and are randomly distributed.
4. Note that electrical conductivity and the type of elements (such as metals) are not defining characteristics of crystallinity; rather, they depend on the material's nature and bonding.
5. Therefore, the best definition of 'crystalline' is that the solid has a highly ordered, repeating three-dimensional arrangement of its constituent particles.