Which of the following observations led Niels Bohr to formulate his model of the hydrogen atom?

• A. Hydrogen gas is colorless and odorless at room temperature.
• B. The emission spectrum of hydrogen consists of discrete lines rather than a continuous spectrum.
• C. Hydrogen atoms have a mass of approximately 1 amu.
• D. Hydrogen atoms can form diatomic molecules under standard conditions.

Answer: (B)

Verified step by step guidance

1. Understand the context: Niels Bohr developed his atomic model to explain the behavior of electrons in atoms, particularly hydrogen, based on experimental observations.
2. Identify the key observation: Bohr was influenced by the fact that hydrogen's emission spectrum shows discrete lines, meaning hydrogen emits light at specific wavelengths rather than a continuous range.
3. Recognize why this matters: A continuous spectrum would suggest electrons can have any energy, but discrete lines imply electrons occupy specific energy levels or orbits.
4. Connect the observation to the model: Bohr proposed that electrons orbit the nucleus in fixed energy levels and that light is emitted or absorbed when electrons jump between these levels.
5. Conclude that the observation of discrete emission lines in hydrogen's spectrum was crucial in formulating Bohr's atomic model, distinguishing it from other properties like mass or molecular formation.