Atoms and Molecules

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atoms and molecules

Key Ideas from the lessons:


  • Anything made up of atoms is matter.
  • It is because atoms take up space and have mass that all matter takes up space and has mass.
  • Atoms are the basic building blocks of matter, and determine the properties and behaviors of all materials.
  • All matter-solids, liquids, and gases-is made up of discrete particles (atoms), rather than being continuous and these atoms are the matter rather than contained in matter. In other words, atoms are not floating or embedded in some of other substance such as air or a liquid–atoms are the air, or liquid.
  • There are more than 100 elements that combine in a multitude of ways to produce compounds, which account for the living and nonliving substances that we encounter.
  • Atoms may stick together in well­ defined molecules.
  • Individual atoms are much smaller than things that can be seen and even much smaller than very small things, such as dust, germs and other microorganisms, blood cells, and plant cells.

These lessons are an introduction (8th grade they go more in depth) to the basics of atoms and molecules.  This basic background knowledge will help students connect to the crosscutting concept of matter and energy. Our theme throughout all units this year is: Within a natural system, the transfer of energy drives the motion and/or cycling of matter. 

Sequence of Lessons’ summary:

Lesson 1: Review main ideas of our previous lessons (What is Matter? And Properties of Matter)Ask students if they have heard of the word atom before. Accept all responses. Tell students that the reason why matter takes up space and has mass is because all matter is made up of atoms and atoms have mass and take up space. Discuss several analogies of bigger things made up of smaller things (like Legos). Introduce students to the periodic table of elements (they have a copy in their student planners). Ask students if they recognize any of the elements. Show What is Matter?  and walk through a tutorial: Atomic Structure. Read the KidsDiscover infographic about the four elements that make up most living things. Make sure students understand that the study of matter is called chemistry and that these elements and the molecules they can create are chemicals. This would be a good time to address students’ misconceptions of the word chemicals: Article: 5 Simple Chemistry Facts that Everyone Should Understand Before Talking About Science.  To understand just how small an atom is I use Video: TEDed: Just How Small is an Atom? and scale of the universe which leads students to asking how scientists can see atoms. I found this video helpful. Video: How can you See an Atom?

Lesson 2: Next I introduce students to molecules. When two or more atoms form a bond—it is called a molecule. If the atoms are different elements, the molecule is called a compound. These videos are helpful: Video: Bill Nye the Science Guy: Atoms and Molecules; Study Jams videoCarbon video series: which links to climate change. Students then build molecules using the PhET simulation . I follow a lesson plan that was submitted by a teacher. It is under “For Teachers”. As another formative assessment, I pass out the “It it made of molecules?” probe by Uncovering Student Ideas in Science, Vol. 1: 25 Formative Assessment Probes**and ask students to engage in argument from evidence. My students then complete a word web for  atom and molecule.

Lesson 3: Watch Video: Dr. Neil deGrasse Tyson: The Most Astounding Fact Ask students to interpret what he is saying. Discuss any reactions to the video. Print and pass out the article: We are Stardust. These are questions that go with the article. Modify them to fit your students’ needs. Afterwards, I pass out the molecule project instructions and go over the expectations (see the resources below). To summarize: students research a molecule that will come up in later Earth Science units: H2O, CO2, O2, N2, NaCl, NH3, SiO2(silica/quartz), CH4, C6H12O6 (glucose), CaCO3 (calcium cabonate), O3,  NaHCO3 (sodium bicarbonate),to name a few.   They will create a poster model of the molecule and write a “brag/whine” narrative essay. The molecule is the narrator. The purpose of the assignment is to give students a BRIEF introduction to molecular structure so they can become familiar and more comfortable when we learn about molecular motion.

Lesson Resources:


Periodic Table: 

Scale size of atoms/molecules:

  • Video: TEDed: Just How Small is an Atom?
  • Teacher PD video: Good Thinking–What’s the “Matter” with Cells and Atoms? — investigates the difficulties students have with applying ideas about matter consistently and appropriately across the life and physical sciences, and with interpreting and relating different representations of microscopic structures.
    Explore the research:
  • scale of the universe

Atoms and Molecules

Interesting Articles/videos:

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