Introduction to the Atomic Structure

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Objective

TSWBAT differentiate between the sub atomic particles in an atom in terms of charge and location. TSWBAT explain the relative size of the atom compared to everyday objects.

Big Idea

Let's take a journey from deep space into the smallest part of all matter-the atom.

Introduction

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 to introduce students to the basic structure of the atom, its sub atomic parts, their charges and the relative size of the atom.  This is aligned with the NGSS Disciplinary Core Idea (DCI) PS1.A (Structure and Properties of Matter): “each atom has a charged substructure consisting of a nucleus, which is made of protons and neutrons, surrounded by electrons”. 

The students explore the atom using two of the NGSS Practices:  (1) Questioning and (2) Developing and Using Models.  Modeling is accomplished by students making a concept map (CM) of the atomic structure that illustrates their understanding based on prior knowledge and then after formal notes have been presented to them.  Their model should change between the two to show that mastery of the standard has been met.  Students begin to “Practice” questioning when they share their concept maps with one fellow classmate and begin to ask questions about the other concept map.  This will be an introduction to questioning and will probably only illustrate lower-order questions based on Bloom’s taxonomy.

The Cross Cutting Concept (CCC) that is illustrated throughout the lesson will be Scale, Proportion, and Quantity because “it is critical to recognize what is relevant at different measures of size, time, and energy and to recognize how changes in scale, proportion, or quantity affect a system’s structure or performance”. It is important to recognize that this is an underling theme and that students will not be summatively evaluated on this part of the lesson.

Engage

15 minutes

This part of the lesson engages students in the idea that there is a vast amount of space that is within the atom relative to the size of its parts.  I introduce the atom by showing the 1977 movie “Power of Ten”.  It is a bit out dated, but exposes students to the parts of the atom and how much space is between the nucleus of an atom and its electrons by comparing it to the universe. The goal of showing this video is not to get students caught up in the math, but instead to introduce thinking about the size of an atom and its subatomic parts.

During the course of the nine minute video, students write down three questions that are used to generate a short classroom discussion after the video.  The conversation starts with questions about the vastness of the universe, but after a little probing and teacher facilitation the students start asking questions about the atom.  I provide some typical student Power of Ten questions that are good conversation starters.  After a few minutes of discussion, this is a good point to introduce the exploration stage of the lesson.

As a alternative to the 1977 Power of Ten video, I have used the more recent IMAX Cosmic Voyage that is narrated by Morgan Freeman.  I use the Power of Ten because the school I teach at is just outside of Chicago and my students can relate to the fact that it was filmed in Chicago, IL. 

Explore

20 minutes

During this part of the lesson students have the opportunity to explore their prior knowledge (see video) of the atom; building a deeper understanding of PS1.A (see Introduction) and how each atom has a charged substructure consisting of a nucleus which is made up of protons and neutrons and is surrounded by electrons.  After students engage in conversation about the Power of Ten, they begin working on the concept map, using the atom concept map cards.  

Some students have not made a concept map before, so I model one for them on the board to eliminate potential confusion (CM video).  The goal of this part of the lesson is to focus on their prior knowledge of the atom, as mentioned in the Engage section of the lesson.   This process is not meant to be perfect, nor graded for that matter, it's just meant to uncover any misconceptions that students might have.

While students are working on their concept maps I monitor their progress and ask questions to gauge their level of understanding, such as:

  • "when have you learned about the atom?
  •  "what did you learn from the movie?" 
  •  "Is there a better connecting word that could be used?" 

Which ever questions you choose, it should allow the students to answer with their own thoughts.  After about 10 minutes of creating the map, I then direct students to explain their concept maps with another student and question any differences that they see between them. There questions at this point in the year will be lower-order questions, such as "why did you design your CM that way?", or "how did you know that protons are positive?".  Here students get more exposure to the NGSS Practice of questioning, develop better communication skills and learning from their classmates.

Explain

10 minutes

Here students take notes on the atom, such as the parts (proton, neutron and electron), their location (nucleus or electron shell), charge (+, - or 0) and what mass they contain.   I draw the Atomic parts diagram on the board, label each of the parts and explain that each sub atomic part has mass.  This leads into the next lesson that show how to calculate mass and atomic number.  The goal is to provide students with a deeper, more accurate understanding of PS1.A and how all atoms have sub atomic parts that have a charge, mass and located either in the nucleus or the electron cloud.  This tends to provide students with enough information to create a more accurate second concept map which is explained in the expand portion of the lesson.

Expand and evaluate (homework)

5 minutes

After students have received notes they can use the rest of the time to start the final version of their concept map (atom concept map cards).  I tell students to create their new map on the opposite side of the first draft so that they can use their prior thinking about the atom as a scaffold to build on with what they have learned during the lesson.  This is a good time to walk around and assess the students' understanding of the atom and see if they have dispelled their misconceptions. Refer to the concept map video from the Explore section for an accurate illustration of a concept map. Students do not have enough time to complete the final concept map in class, so it will be assigned as a take home assessment.   

The next class will start with a quick warm-up about the parts of the atoms, and will continue with some student examples of concept maps.  I further instruct students to look in their textbook if they have any further questions about the atom, or guide them to Chem4Kids.com if they want to use the web for research. 

Post-Lesson Reflection/Student work.

At this point in the year I realized students really struggle with how to make a concept map because many have not seen one before (see before and after concept map pictures).  They also struggled with the idea that it’s okay to be wrong because prior knowledge is not perfect.  The students that struggled I encouraged them to do the best they can, this helped them through the initial concept map.

I found that the most helpful thing for students is for them to share their work with one another.  This showed them there are many right ways to make a concept map and not everyone has the same prior knowledge.  The student CM sharing, coupled with my finished product, really built a great foundation for further understanding of atomic structure.