---
title: "The Bohr model accurately predicts the discrete energy levels and emission spectrum wavelengths for singly ionized helium (\\(\\text{He}^+\\)), which possesses a single electron, but fails to predict the spectrum of neutral helium (\\(\\text{He}\\)), which possesses two electrons. Which of the following best explains why the Bohr model cannot be directly applied to neutral helium?"
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url: "https://nerd-notes.com/ubq/116512/"
date_modified: "2026-08-04T05:02:20+00:00"
---

# The Bohr model accurately predicts the discrete energy levels and emission spectrum wavelengths for singly ionized helium (\(\text{He}^+\)), which possesses a single electron, but fails to predict the spectrum of neutral helium (\(\text{He}\)), which possesses two electrons. Which of the following best explains why the Bohr model cannot be directly applied to neutral helium?

The Bohr model accurately predicts the discrete energy levels and emission spectrum wavelengths for singly ionized helium (\(\text{He}^+\)), which possesses a single electron, but fails to predict the spectrum of neutral helium (\(\text{He}\)), which possesses two electrons. Which of the following best explains why the Bohr model cannot be directly applied to neutral helium?

- **A.** The second electron in neutral helium shields the nucleus completely, eliminating the net electrostatic force acting on the outer electron.
- **B.** Electrostatic repulsion between the electrons introduces multi-body interactions and shielding, so the energy levels cannot be calculated using a single-electron central force model.
- **C.** The presence of two electrons causes the nuclear mass to recoil significantly, breaking the assumption that the nucleus remains stationary at the center of the atomic orbit.
- **D.** Photons emitted during transitions in neutral helium continuously scatter off the second electron, causing the energy levels to become non-quantized.

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