Which phrase accurately describes an atom?

• A. A small, dense nucleus surrounded by electrons in a cloud
• B. A structure made only of neutrons and electrons
• C. A solid sphere composed entirely of protons
• D. A molecule formed by the combination of two or more elements

Answer: (A)

Verified step by step guidance

1. Recall the basic structure of an atom: it consists of a nucleus and electrons surrounding it.
2. Understand that the nucleus is small and dense, containing protons and neutrons.
3. Recognize that electrons are not solid particles orbiting like planets but exist in a cloud-like region around the nucleus.
4. Eliminate incorrect options: atoms are not made only of neutrons and electrons, nor are they solid spheres of protons, and they are not molecules (which are combinations of atoms).
5. Conclude that the phrase 'A small, dense nucleus surrounded by electrons in a cloud' accurately describes an atom.