## Chapter 38: Spectral Lines, Bohr’s Theory, and Quantum Mechanics

### Study Plan

When a sample of a chemical element is heated, often by means of an electric discharge, it emits characteristic electromagnetic radiation of discrete wavelengths.

In our study of the spectra of hydrogen, we will be able to ask:

• The spacings between these lines decrease systematically from right to left, from long wavelengths to short wavelengths. This systematic pattern suggests that the wavelengths form a series, described by a simple mathematical formula. What is this formula? (Section 38.2, page 1291)
• Are there other series of spectral lines in the spectrum of hydrogen? What are they, and what is the shortest wavelength in any of these series? (Section 38.2, and Example 1, page 1292)
• How can we calculate the wavelengths of the series from the quantum processes within the hydrogen atom? (Example 2, page 1300)
• What series of wavelengths will hydrogen absorb, when illuminated with light containing a wide range of wavelengths? (Example 3, page 1301)

#### Organize

1. Prepare for lecture by reading the assigned sections from Chapter 38 in your textbook or ebook. This will provide an organizing framework for concepts introduced in lecture, and help you take better notes.
2. Take the checkup quiz and work the Checkup questions in your textbook to assess your understanding of basic concepts. Take note of any topics you need to review further.
3. Review the Examples from your textbook. These progress from simple to complex, and provide concrete illustrations of the concepts discussed.

#### Learn

2. Access the Online Concept Tutorials given for this chapter. Tutorials use animation and interactive exercises to help develop your understanding of fundamental topics.
Bohr Model of the Atom
Sections: 38.1, 38.2, 38.4
3. Use the FlashCards to test your memory for new key terms and equations.
4. Work the end of chapter Problems and Review Problems assigned by your instructor. If your instructor has assigned SmartWork online homework, login from the right navigation pane.

#### Connect

1. Throughout the text Physics in Practice boxes explore real-world applications of core concepts in specific detail. In Chapter 38 see:
 Physics in Practice: Ultramicroscopes
2. Physics in the News offers additional real-world physics applications, and a daily dose of science-based news.