Which revolutionary idea did Niels Bohr introduce to modify the atomic model regarding the behavior of electrons?

• A. Electrons are embedded within the nucleus.
• B. Electrons move in elliptical orbits around the nucleus.
• C. Electrons are randomly distributed throughout a positively charged sphere.
• D. Electrons occupy specific, quantized energy levels and orbit the nucleus without radiating energy.

Answer: (D)

Verified step by step guidance

1. Understand the historical context: Before Bohr, the atomic model (like Rutherford's) described electrons orbiting the nucleus but couldn't explain why electrons didn't spiral into the nucleus due to energy loss.
2. Recognize Bohr's key contribution: He proposed that electrons move in specific, fixed orbits or energy levels around the nucleus, rather than any arbitrary path.
3. Learn about quantization: Bohr introduced the idea that these orbits correspond to quantized energy states, meaning electrons can only exist in certain allowed energy levels.
4. Note the stability aspect: According to Bohr, electrons in these quantized orbits do not emit energy as radiation, which explained the stability of atoms and discrete spectral lines.
5. Summarize the revolutionary idea: Electrons occupy specific, quantized energy levels and orbit the nucleus without radiating energy, modifying the classical atomic model significantly.