Exploring the Periodic Table
Lesson 2 of 12
Objective: TSWBAT Differentiate between metals and nonmetals in terms of number of valence electrons, electron behavior and reactivity. TSWBAT
This lesson addresses the NGSS 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".
The goal of the lesson is for students to begin to build a basic understanding of the periodic table, including metal vs. nonmetals, families, basic trends and valence electrons. This is aligned with the NGSS Disciplinary Core Idea (DCI) PS1.A: The periodic table orders elements horizontally by the number of protons in the atom’s nucleus and places those with similar chemical properties in columns. The repeating patterns of this table reflect patterns of outer electron states.
In this lesson students explore the periodic table using the NGSS Science Practice 2: Developing and using models. The activity has students explore various websites and build a mental model of patterns that are present throughout the periodic table. This lesson continues to build on the Crosscutting Concept of Patterns by showing students that one of the ways the periodic table is arranged is by families based on valence electrons. This is a key concept that will be seen throughout the entire course.
At the beginning of a unit I like to see what prior knowledge my students bring to the table, which in this case is knowledge about the periodic table. A great way to accomplish this is by using a K-W-L which has students write down what they think they know (K), what they want to know (W) and at the end of the lesson or objective what they learned (L). A variation on this that I use is instead of the “W” portion being what they want to learn I have them write down questions that build on what they already know. I find that this is easier for them, in addition to building on the NGSS practice of questioning. The NEA has a good explanation how to modify K-W-Ls.
I instruct students to write "Periodic Table" as the topic and fill in the K and the W boxes with a minimum of 5 responses for each category. After several minutes of brainstorming and writing, I have them briefly pair-share with a person close by, followed by a brief class discussion about facts and questions they have.
A common misconception that is revealed at this point is that the periodic table is divided into metals and gases. Many students confuse nonmetals as strictly being gases. This misconception will be corrected as they perform the webquest.
After a brief discussion, I collect the students' K-W-Ls so that I can review what they have written while working on the webquest. I will redistribute this the end of the next day’s lesson as a formative assessment of the two day objective.
I Like using a K-W-L because it helps students realize what their misconception are by comparing and contrasting what they thought they knew to what they've learned. This process is an authentic, student centered way for them to develop a personalized body of knowledge that longer-lasting.
Another benefit to a K-W-L is that it can be used to summarize a small grain size of information (nonmetals vs. metals) or a larger grain size like a unit concept (periodicity). Either way it makes students self-evaluate what they knew to what was learned.
While they are working on their K-W-L I pass out the webquest. I immediately have students log-in and begin the webquest individually. To make things more efficient, I instruct students to visit my school page and use the document that I posted there to navigate to the websites. This saves a lot of time by having students click on a link instead of typing in the website’s URL, which they might do incorrectly.
Since this is part of a two-day activity that will be coupled with coloring the periodic table (Unit 3, lesson 3), I let students know they need to work efficiently so that both assignments can be completed on time. Since the goal of this lesson is to let students discover the periodic table, I also let them know they should not spend too much on Part I: The Major Players.
It’s not that Part I is unimportant, but some of the information in this part is difficult for some students to find because of their reading level. This is an area where the lesson can be differentiated based on reading level (see reflection).
While students are working on this I look over their K-W-Ls and assess where misconceptions are present. This process does not take long and allows me to walk around and assess what my students are learning. If students are struggling with finding the information, particularly in Part I, I will direct them to the next website and revisit the difficult parts.
The goal of the webquest in Part II is for students to realize that the periodic table is arranged by groups and periods, that metals, metalloids and nonmetals are in specific areas, and that an element's location provides a lot of information about it.
In part III they will begin to see what specific characteristics each group (family) on the table has. Both of these sections are very easy for them to navigate and allow most students to complete the assignment in one class period (see webquest key).
I remind students that with five minutes left they need to consider wrapping up the assignment, and if they have not completed the webquest (student work) they will have time tomorrow.
The webquest serves as a good introduction to periodic table because it covers a large breadth of information in a short period of time. A Large breadth of information is traditionally difficult for student, however, this webquest helps eliminate this problem by providing animation and pictures that help students visualize periodic table concepts. They then can use the pictures to create a mental model as we get more in-depth into the periodic table throughout the unit.
While they are logging off of their computers I put a Post-it Note in front each student which builds curiosity. After all students have logged off I ask each student to write down their muddiest point -- the thing they find most confusing-- about the periodic table. As they leave the room they can put it on the wall by the door on their way out of the classroom.
I like using this technique because it requires them to self-assess what they have learned by saying what they don't know. It’s an excellent reinforcement that forces them to independently think and ties in nicely with the K-W-L.
I then take the information from the Post-it notes and direct my instruction accordingly. In this case students were still confused about what a valence electron is and what it says about an element. Therefore, I focused my subsequent instruction on what valence is, and really made sure that my future lessons clarified this concept.