In chemical structures, what do square brackets typically indicate?

• A. An ionic bond between ions
• B. A covalent bond between two atoms
• C. A hydrogen bond between molecules
• D. The presence of a complex ion or coordination compound

Answer: (D)

Verified step by step guidance

1. Understand that in chemical notation, different types of brackets and symbols convey specific structural or bonding information.
2. Recognize that square brackets \(\left[ \ \right]\) are commonly used to enclose complex ions or coordination compounds, indicating a group of atoms or ions acting as a single entity.
3. Note that ionic bonds are typically represented by the juxtaposition of ions with their charges, not by brackets.
4. Recall that covalent bonds are shown by lines between atoms, and hydrogen bonds are often indicated by dashed lines or dotted lines, not by brackets.
5. Therefore, square brackets signify the presence of a complex ion or coordination compound, grouping the central metal ion and its surrounding ligands together.