SWBAT model atomic structure.

Making models out of candy is a middle schoolers' dream! Students explore atomic structure in a sweet way.

15 minutes

Physical models for physical learners - this lesson provides students with opportunities to use the periodic table to determine atomic structure and build accurate physical models using gumdrops and toothpicks. Developing models to describe unobservable mechanisms (**SP2**) helps students conceptualize atomic composition which is a precursor to the modeling of simple molecules and extended structures (**MS-PS1-1**). A basic understanding of atomic structure is fundamental to further study of molecules, chemical reactions and properties of matter. As students build, they also process the structure and function cross cutting concept. They recognize that* **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*.

This is a stand alone investigation or can be used as part of a unit of study with the following lessons:

Building Atomic Models Simulation Investigation

Atoms Family Atomic Structure Review

Periodic Table of Elements Exploration Project

In order to ENGAGE students in this lesson, students respond to the questions posed in the Cooking Up Atoms Investigation Warm Up. This warm up acts as a mini-lesson to instruct students on how to determine the number or protons, neutrons and electrons using an entry from the periodic table. Depending on the previous exposure to using the periodic table, students may require more or less instruction and practice. In addition to the mini-lesson, students experience how models help visualize concepts that are difficult to observe. During this experience, students discuss:

**What are scientific models and how do models help us?**

This question directs a class discussion that helps students complete the Background Information section of the Cooking Up Atoms Investigation. To see what this work looks like completed, visit: Cooking Up Atoms Investigation - Student Work. If students need a little more background information to help them explore models, the What is a scientific model video is fun:

40 minutes

The EXPLORE stage of the lesson is to get students involved in the topic so that they start to build their own understanding. To help students explore, students follow the procedure in the Cooking Up Atoms Investigation:

Students:

1) Complete Columns 1 and 2 in Data Table 1 for Lithium.

2) Make a model of a Lithium atom:

- Collect gumdrops, toothpicks, and wooden skewers.
- Choose one color to represent protons, another color to represent neutrons and a third color to represent electrons. Include these colors in a key.
- Combine protons and neutrons in one cluster (using toothpicks broken in half) to form the nucleus.
- Place each of the electrons on one end of a skewer, and stick the other end of the skewer into the nucleus to make a complete atom.

3) Draw your Lithium atom in data table 1. Don’t forget to label your drawing with protons, neutrons, electrons, nucleus, and electron cloud!

4) Choose at least two other atoms with an atomic number smaller than 7. Complete Data Tables 2 and 3. Label or make a key.

5) Answer the conclusion questions and ask for your Check-Out Quiz.

**Teacher Note: **The only materials needed for this investigation are gumdrops, toothpicks and wooden skewers. Plan ahead for extras and encourage students to reuse the supplies. Limiting students to smaller atoms (I suggest atomic number 7 or less) helps to limit the overuse of supplies. For safety purposes, remind students that eating the gumdrops is not safe practice. For motivation, I provide students with clean samples once they have completed the investigation and evaluation. A second note, while I give students explicit instructions on how to make the models, I'll have students think about how they might make the models first. Asking students to make their own creative models and then revise those models using feedback is an important part of the modeling process.

20 minutes

The EXPLAIN stage provides students with an opportunity to communicate what they have learned so far and figure out what it means. This stage of the lesson presents a great place for a quick formative assessment. To explain what they have learned, students complete the analysis questions on page 3 of the Cooking Up Atoms Investigation. These questions help students prepare for the performance assessment in the EVALUATE stage of the lesson. Examples of answers Atomic Models Investigations Final PACER Arguments Student Work 1 and Atomic Models Investigations Final PACER Arguments Student Work 2 show how answering the analysis questions based on the investigation can help students formalize their understanding.

The EXTEND stage allows students to apply new knowledge to a novel situation. The novel situation in this case is to think about atomic structure in terms of scale. The Scale, Proportion and Quantity cross-cutting concept suggests: *Time, space, and energy phenomena can be observed at various scales using models to study systems that are too large or too small* (**CCC**). Students explore this concept as they solve the following problem:

The typical atom has a diameter of 10-10 meters. The typical nucleus has an average diameter of 10-15 meters. This means, that on average, an atom has a diameter that is 105 or 100,000 times bigger than its nucleus! Using a ruler and this scale, determine where on the map electrons would be using objects in the classroom as nuclei. Draw and label your atomic radius on the map above. For a student example of the solution, visit: Building Atomic Models Extension. For discussion of using cross-cutting concepts, watch this section's reflection: Using Cross-Cutting Concepts for Extension Opportunities.

20 minutes

The EVALUATION stage is for both students and teachers to determine how much learning and understanding has taken place. For this investigation, students complete a performance assessment to show that they can model and explain atomic structure. Students use the model supplies and a copy of the Building Atomic Models Performance Assessment to create and explain an atomic model of an element chosen from the Periodic Table. The following questions can be utilized to probe student understanding and prompt explanation of the their model:

**1) What do the different color gumdrops represent in your model?**

**2) Why do we need to use this simulation to model atoms?**

**3) Which types of particles are located in the nucleus?**

**4) Where do the other particles go?**

**5) Why can't protons be close to each other? What particles provide spacing?**

**6) Where is most of the mass of the atom found?**

**7) How did you determine the number of protons/neutrons/electrons in your model?**

**8) What parts of your model are accurate?**

**9) What parts of your model are inaccurate?**

For examples of student explanations, watch these:

Independent student explanations (1 & 2):

Student explanations with teacher probing questions:

In addition to the performance assessment, review of student analysis questions from page 3 of the Cooking Up Atoms Investigation provides insight into student learning.