Which of the following models best helps explain the basic structure of an atom to a beginner?

• A. A solid sphere with no internal structure
• B. A cloud of protons and electrons mixed together without any central nucleus
• C. A nucleus made only of electrons, with protons and neutrons orbiting around it
• D. A nucleus containing protons and neutrons, with electrons orbiting in defined energy levels around it

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the historical development of atomic models, starting from the simplest to more complex ones, to see how scientists refined their understanding of atomic structure.
2. Step 2: Recognize that the 'solid sphere with no internal structure' model is an early idea (Dalton's model) that does not explain subatomic particles or internal structure.
3. Step 3: Note that the model describing a 'cloud of protons and electrons mixed together without any central nucleus' is incorrect because protons and electrons are not randomly mixed; the atom has a central nucleus.
4. Step 4: Understand that the model with 'a nucleus made only of electrons, with protons and neutrons orbiting around it' is incorrect because the nucleus contains protons and neutrons, not electrons.
5. Step 5: Conclude that the best model for beginners is the one with 'a nucleus containing protons and neutrons, with electrons orbiting in defined energy levels around it,' as it accurately represents the atom's structure and introduces the concept of energy levels.