Yes, that's a key characteristic of a pure substance. Here's why:

* Pure substances are made up of only one type of particle. This particle can be an atom (like gold, Au) or a molecule (like water, H₂O).

* Examples:

* Elements: Iron (Fe), oxygen (O₂), carbon (C)

* Compounds: Sodium chloride (NaCl), glucose (C₆H₁₂O₆)

* Impurities: A pure substance doesn't contain any other substances mixed in with it. If you have a mixture, like salt and pepper, it's no longer a pure substance.

Think of it this way: A pure substance is like a single ingredient, while a mixture is a combination of multiple ingredients.