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Lesson 2 Matter

  Interactive Activity

Element Builder © Gizmo


Background Information:

Please review this simulation to help you visualize and understand the structure of atoms and isotopes.

Please note: If you scroll down while in the Gizmo, you will see a list of questions. You DO NOT need to complete these questions. You are able to complete them for extra practice if you would like.


  1. Click on the play icon to open the virtual lab. Print students can access the Gizmo in the Online Resources for Print Students section of their online course.
  2. Click on “Show element name,” “Show element symbol,” “Show electron dot diagram,” and “Show Group and Period.”
  3. Add one electron to make a neutral particle of hydrogen-1. Note the structure and the element notation.
  4. Click on the play button.
  5. Add one neutron to make a neutral particle of hydrogen-2. Note the structure and the element notation.
  6. Add one more neutron to make a neutral particle of hydrogen-3. Note the structure and the element notation.
  7. Create a stable structure for helium-4 by adding one proton and one electron. Note the structure and the element notation.

    What do you need to do to create an isotope of helium-4?

    Add or remove one or more neutrons.
  8. Create a stable structure for lithium-6 by adding one proton, one electron, and one more neutron. Note the structure and the element notation.

    Is lithium-6 the most abundant isotope?

    No, lithium-7 is the most abundant isotope.
  9. Create a stable structure for fluorine-19. Note the structure and the element notation.
  10. Create a stable structure for aluminum-27. Note the structure and the element notation.
  11. Click on the analysis tab to complete the analysis questions.
  1. What happens when more than two electrons are in an element’s structure?

    They move farther out to fill the next energy level that is available.
  2. Use the element builder to create the following isotopes and fill in the missing information from this table.

    Isotope Name
    		 magnesium-25 chlorine-35
    Number of Protons
    		 15
    Number of Neutrons 18
    Mass Number
    		 18 15
    Number of Electrons 8
    Group Number
    		 15
    Number of Valence Electrons 5
    Period Number
    		 2
    Number of Energy Levels 2

    Isotope Name
    		 magnesium-25 phosphorus-33 chlorine-35 oxygen-18
    		 nitrogen-15
    Number of Protons
    		 12 15 17 8 7
    Number of Neutrons 13 18 18 10 8
    Mass Number
    		 25 33 35 18 15
    Number of Electrons 12 15 17 8 7
    Group Number
    		 2 15 17 16 15
    Number of Valence Electrons 2 5 7 6 5
    Period Number
    		 3 3 3 2 2
    Number of Energy Levels 3 3 3 2 2