Which statement describes the concept that electrons move around the nucleus in fixed orbits called electron shells?

Which statement describes the concept that electrons move around the nucleus in fixed orbits called electron shells?

• A. The atom is a solid, indivisible particle with no internal structure.
• B. Electrons are located in a diffuse electron cloud around the nucleus.
• C. The nucleus is a central region containing protons and neutrons.
• D. Electrons move around the nucleus in fixed orbits called electron shells.

Answer: (D)

The idea being tested is that electrons move around the nucleus in fixed paths called electron shells. This reflects the Bohr model, where electrons occupy specific, defined orbits at set distances from the nucleus, forming distinct shells and energy levels. This explains why electrons stay at particular distances and can jump between levels, producing discrete spectra. The other statements describe different ideas: a solid, indivisible atom with no internal structure belongs to an older, simplistic view; a diffuse electron cloud points to the modern quantum model where electrons occupy probabilistic regions rather than exact orbits; and the description of the nucleus as a central region with protons and neutrons focuses on the nucleus itself, not on electron motion.

The idea being tested is that electrons move around the nucleus in fixed paths called electron shells. This reflects the Bohr model, where electrons occupy specific, defined orbits at set distances from the nucleus, forming distinct shells and energy levels. This explains why electrons stay at particular distances and can jump between levels, producing discrete spectra. The other statements describe different ideas: a solid, indivisible atom with no internal structure belongs to an older, simplistic view; a diffuse electron cloud points to the modern quantum model where electrons occupy probabilistic regions rather than exact orbits; and the description of the nucleus as a central region with protons and neutrons focuses on the nucleus itself, not on electron motion.