In this lesson students learn about the behavior of electrons and emission spectra. They do this through taking notes based on a Powerpoint, performing a lab, and doing practice questions.
In this lesson students perform a flame test lab. For the lab each group requires one Bunsen burner, 7 test tubes with solutions, metal tweezers or tongs, wood splints soaked in the solutions, and spectroscopes. It is helpful to soak the splints in the solutions overnight. I use Barium chloride, Calcium chloride, Copper II chloride, Lithium chloride, Potassium chloride, and Strontium chloride. There are many options of salts that you can use for the lab so use what is available in your lab. The major color that will be seen is the cation so nitrates are also an option.
To begin the notes I introduce electromagnetic radiation and waves including wavelength, amplitude, frequency. I also teach students how to solve problems using the speed of light and planck's constant equations. The first portion of the notes are on slides 2-8 of the Powerpoint.
When performing the practice questions in the notes I make sure to review the "plug and chug" technique of problem solving by underlining what students know, circling what they want, and figuring out how to get there (which equation). My reflection on Problem Solving in Chemistry for Unit 1 lecture 5 temperature goes over this technique in detail.
I then introduce emission spectra and how electrons emit different colored lights when they fall back to their ground state on slides 9-15.
This is a copy of the filled in notes with worked examples.
Students have the most trouble with determining the proper equation to use when solving the math problems and using scientific notation when plugging into their calculators. To help with this I go over the problems with them and make sure to reiterate how to plug into their calculators properly.
For this section students perform a Flame Test Lab to reinforce the idea that each element produces different colors when they are excited and fall back to their ground state.
To check for understanding concerning the concepts in the lesson I have students perform the practice homework which is on the last page of the notes. I have students begin the homework practice as they get done with the lab and complete for homework. I stamp the homework for completion the next day and go over answers using the answer key. The most common mistakes students make are using the incorrect equations, or plugging the values into the calculator without using parentheses to ensure correct order of operations, thus getting the wrong answer.