Lesson 6 of 13
Objective: SWBAT recognize properties endemic to metals and nonmetals, and explain their reactivity based on electron behavior.
This lesson contains the following alignment to 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. After students learned yesterday how metals have less valence electrons and give them up, we will move further into properties of elements today.
Structure and Function Cross Cutting Concept: We are engaging this concept at the middle school level which states "Complex and microscopic structures and systems can be visualized, modeled, and used to describe how their function depends on the shapes, composition, and relationships among its parts; therefore, complex natural and designed structures/systems can be analyzed to determine how they function." I bolded the particular portions that apply to this lesson, as we will be talking about how the types of elements used affect the function of a product, and how we choose materials based on their properties.
I am choosing to deliver this information via PowerPoint to save time. I was about a week behind some of my colleagues in the curriculum. While I would have loved to have students explore and observe samples of metals and nonmetals to build this understanding, time does not allow for it at this point.
To open the class, I pass out Probe #1: Pennies, from Uncovering Student Ideas in Science Vol 3 from NSTA Press. Due to copyright laws, I can not post a screenshot of the activity here.
The activity asks students to select which things out of a list of 14 properties describe the atoms that make up the shiny new penny. At the end, students have to write why they selected particular things off the list.
This is particularly good for my students as a review of the atom, as two choices are that the atoms are made of smaller particles and contain mostly empty space. Another reason I like this is that it previews some properties of metals we will discuss today, such as luster, color, state at room temperature, etc. This probe also forces students to differentiate between what is a property of a penny, vs what is the property of the atoms that make up the penny.
Students usually will ask about whether atoms have color as a result of this activity, or if atoms themselves are shiny. This makes a good discussion heading into our notes.
I ask students to get their binder open to where they take notes, and turn on the projector with our Properties of Elements PowerPoint.
We begin by defining properties. I ask students to give me three physical properties of my shirt. They describe the color, the size, and usually that it is solid. I then ask for a chemical property of my shirt. Here they stumble -- so I prompt with "How could you make this shirt react?" and a student in each class will respond with "Burn it?". I seize upon that to point out how observing chemical properties use up the substance, whereas we can observe the physical properties without using the substance.
Next we go further into the three types of matter as represented on the periodic table. I provide them a physical property of each, and then a chemical property -- how they interact at the valence level. I reinforce the connection with where the elements are on the periodic table and their behavior -- metals on the left side are losing electrons to be like the noble gas above them, whereas non-metals on the right side are gaining electrons to be like the noble gas on the end of the period.
As we get into physical properties of metals, I connect their conductivity to the ability to lose electrons and how the flow of electrons creates electric current. Students ask about their phones usually, and we discuss why lithium makes a good battery being lightweight and wanting to give up a single electron. Students usually understand the ideas of luster and malleability, but struggle with ductility. To explain how to draw a metal into a wire, I demonstrate like this.
When I explain the chemical properties of metals, I describe how acids want the electrons from metals. I tell students about how our old chemistry labs had the pipes underneath them fail from students not disposing of chemicals properly, and how one day the pipes burst and flooded the social studies class below them.
When discussing the physical properties of non-metals, I take a hammer to a piece of lump sulfur, so the students can see how it shatters. We discuss how they want electrons, so they are good at protecting and insulating us from electricity.
When I explain the chemical properties this year, I point out that non-metals now have a song about them, and I poorly sing the chorus from "All about that Bass". It is important to break up a long session of sitting and taking notes from PowerPoint with something. That break can be a chemical demo, maybe a stretch break, or in this case, the teacher making a fool of himself. The students have a little laugh at my singing, but then we talk about drain cleaners and how they work on dissolving food and hair that might be clogging up the drain.
Last I talk very quickly about metalloids- and I use the term "confused" while describing them. I discuss how some of them have more metallic properties, while others have more properties of non-metals, but that this flexibility has advantages for us in designing electronics. We talk about how silicon computer chips can conduct electricity, but that they get very hot while doing so. This prompts students to ask about their phones feeling warm when they're using/overusing them. We differentiate between the battery heat and processor heat, and I have them think about the heat from our classroom computers.
Now I pass out our Burner Skills and Metals Lab. Students are excited to be doing a real lab, as am I, because the semester has started rather dryly.
I explain that we are doing the lab the following day, but that we want to prepare for the lab. I ask them to read the lab purposes first, while I gather materials from the back of the room.
When students finish, we review the two purposes, to both build lab skills and observe a chemical reaction. Students are excited to work with the burners for the first time. I demonstrate each lighting technique in the front of the room at the teacher lab- first with the matches, then the lighter, and last with the striker. I emphasize how the matches and lighter have to be lit BEFORE turning on the gas, but that the striker has to have the gas turned on first. I show students how our gas nozzles work, with off being perpendicular in either direction, and anything in between allowing the gas to come out.
Many students are afraid of the burner, so we discuss being respectful of the equipment versus being afraid. I talk about how this is less dangerous than their stove top at home, because it is more controlled when we work carefully.
Next I explain chemical disposal, and how we use a waste beaker. I refer back to the story about the old chemistry class pipes breaking because of improper disposals. I remind them that there are always instructions on how to dispose of the chemicals, and ask students to scan Part 2 of the lab to find the disposal instructions and underline them.
We finish with a close read of part 2, pointing out how the name and symbol of the chemicals are provided to help students find them easier in the lab box. I ask what else they have to do in step 1, to get students to notice that they have to record the appearance and create Lewis dot diagrams for the elements. I ask them to read through and circle everything they have to write during this part of the lab. We then review that they need observations during the reaction, and after the reaction.
If time permits, I ask students to continue reading and annotating the rest of the lab. If time is short, I tell them to do it overnight for homework. I remind students of the need for appropriate shoes and hair ties for the next day. After school, I remind students again about proper attire via Remind.com, once at 7pm and again at 6:30am.