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)