Question

How does the electron-cloud model describe electrons?
The exact position of an electron can be known.
An electron can be found at certain distances from the nucleus.
An electron has a high probability of being in certain regions.
Each electron follows a specific path around the nucleus.

Answer 1

The electron-cloud (quantum) model describes electrons as probability distributions (given by the square of the wavefunction), not as tiny balls on fixed tracks. So:

- "The exact position of an electron can be known." — False. Due to the quantum (wavefunction) description and the Heisenberg uncertainty principle you can only assign probabilities, not an exact simultaneous position and momentum.
- "An electron can be found at certain distances from the nucleus." — True (with a nuance). Electrons have quantized energy states and radial probability distributions; certain radii (e.g., most-probable radii) are more likely, though the electron is not restricted to a single exact distance.
- "An electron has a high probability of being in certain regions." — True. Orbitals are regions in space where the probability density is relatively high.
- "Each electron follows a specific path around the nucleus." — False. Electrons do not follow classical trajectories in the atom; the cloud represents probability, not a path.