Question

What is a main difference between the modern atomic model and Bohr's planetary model?

Electrons closer to the nucleus have more energy than electrons further from the nucleus.

Electrons do not orbit the nucleus on fixed paths.

Protons exist in the nucleus, and electrons are in the space outside of the nucleus.

All of these are correct.

Answer 1

The main difference between the modern atomic model and Bohr's planetary model is that **electrons do not orbit the nucleus on fixed paths** in the modern atomic model. Instead, the modern model, based on quantum mechanics, describes electrons as existing in probabilistic cloud-like regions or orbitals around the nucleus, rather than in fixed orbits.

While the other statements contain elements of truth, the key distinguishing feature that sets the modern atomic model apart from Bohr's is the nature of electron behavior and distribution, thus the correct choice in this context would be focused on the fixed paths aspect.

So, while not all answers precisely represent the main difference, it is accurate to say that the most significant difference highlighted here is that electrons do not follow fixed orbits.