Which statement best describes the current (quantum mechanical) model of the atom?

• A. Electrons occupy orbitals, which are regions of space with high probability of finding an electron; their exact positions cannot be known simultaneously with their momenta.
• B. All positive charge is spread uniformly throughout the atom with electrons embedded in it.
• C. Atoms are solid, indivisible spheres with no internal structure.
• D. Electrons move in fixed circular orbits around the nucleus at specific radii, like planets orbiting the Sun.

Answer: (A)

Verified step by step guidance

1. Understand that the quantum mechanical model of the atom is based on the principles of quantum mechanics, which describe the behavior of particles at atomic and subatomic scales.
2. Recognize that electrons are not described as particles moving in fixed paths (orbits), but rather as existing in regions of space called orbitals, where there is a high probability of finding an electron.
3. Recall the Heisenberg Uncertainty Principle, which states that it is impossible to know both the exact position and momentum of an electron simultaneously, highlighting the probabilistic nature of electron location.
4. Compare the given statements to these principles: the model does not treat electrons as fixed orbits (like planets), nor does it describe the atom as a solid sphere or with positive charge spread uniformly.
5. Conclude that the best description is the one stating that electrons occupy orbitals, which are regions of space with high probability of finding an electron, and their exact positions cannot be known simultaneously with their momenta.