Students will be able to explain how electrons are located in energy levels and how to determine the number of valence electrons for atoms through completing an inquiry-style paper.

Electrons are located outside the nucleus in energy levels.

In this lesson students begin to learn about where electrons are located in terms of energy levels and the definition of valence electrons. I have found that a lot of students get confused on electron configuration so it is helpful to have them start to visualize electron configuration with Bohr Models BEFORE I teach full electron configuration. Students also take a mid-unit quiz on what they have learned in the Unit up to this point.

- This lesson aligns with NGSS Physical Science Performance Expectation (HS-PS1-1):
*"Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms"*. - This lesson highlights NGSS Science and Engineering Practice 2:
*Developing and using models*because it leads students in working with Bohr models to understand the electron configuration of elements. - In addition, students are constantly asked to look for patterns in understanding how to determine where electrons are located for atoms. Therefore this lesson deals with NGSS Crosscutting Concept 1:
*"Patterns"*.

The paper that I use for Electron Configuration Part I is adapted from Living By Chemistry's lessons on Electron Configuration. Living By Chemistry is a great book that often leads students into understanding concepts using inquiry and real-world examples. To learn more about this great resource visit their website.

10 minutes

In this section students review what they already know about Bohr models to revisit their ideas about subatomic particles.

Although this is something that we have just learned, it is very helpful to review the ideas.

I give students about 5 minutes to try them on their own and then review the ideas with them. As I go over the answers I fill out on a blank copy of the worksheet.

Because of copyright issues I cannot post this worksheet. I found a similar activity online from the Science Spot and produced by T. Trimpe (2002) which leads students through determining how to perform Bohr models and some of the trends of Bohr models. This is a link to the pdf worksheet.

40 minutes

The goal of this lesson is to have students use their knowledge of Bohr Models to determine how electrons are located in energy shells around an atom's nucleus. This paper is adapted from a Living By Chemistry lesson on electron configuration.

The paper uses an inquiry approach to allow students to figure out the patterns of electrons on their own. By allowing students to do this they are better able to understand the concepts.

I give students time to work on the problems on their own, a few questions at a time, and walk around to help.

Some students are not sure how to fill in the Bohr Models so I individually explain to them that they need to look at the patterns of the elements before and after the empty box.

As I review Bohr models I make sure to highlight the patterns.

Because of copyright issues I cannot post this worksheet but you can use the lesson that I mentioned in the engage section.

20 minutes

Students have time to begin the homework as the get done with the practice. The homework is practice of determining subatomic particles and beginning electron configuration. The homework is due the next day where I stamp it for completion and go over answers using the answer key.

Most students do well on the homework with the only common mistake of placement of electrons in energy shells (2, 8, 18)

20 minutes

For the last part of class I give students a quiz related to the first part of the unit (matter, subatomic particles, molar conversions, and Bohr models). Students turn in their quizzes and I grade using the answer key. The next day students come into class, write their percentage, and perform quiz corrections. I have students work on their quiz corrections to gain mastery of what they missed so there are several things I stress to them:

- Use your notes first when trying to figure out the correct answer.
- Use your partners second to figure out the correct answer.
- Ask the teacher as your last resort if you cannot figure out the correct answer or need additional clarification.

To understand how I have students perform quiz corrections and my rationale for quiz corrections see my reflection for Unit 1 lesson 5.

On this particular quiz a lot of students missed the questions regarding mole conversions (questions 4 and 5), Rutherford's discovery (question 8) and how to calculate the number of neutrons (question 7). To see how this will impact my teaching please see the reflection on Impact of Quiz on my Teaching.