Which of the following best describes what composes an element?

• A. Ions with varying numbers of electrons
• B. Molecules made of different types of atoms
• C. Atoms with the same number of protons
• D. Compounds formed by chemical reactions

Answer: (C)

Verified step by step guidance

1. Recall the definition of an element in chemistry: an element is a pure substance consisting entirely of one type of atom.
2. Understand that atoms of an element all have the same number of protons in their nuclei, which defines the element's identity.
3. Recognize that ions are atoms or molecules with a net electric charge due to loss or gain of electrons, but an element itself is defined by protons, not electrons.
4. Note that molecules made of different types of atoms represent compounds or mixtures, not a single element.
5. Conclude that the best description of what composes an element is 'Atoms with the same number of protons' because this is the fundamental characteristic that distinguishes one element from another.