Atomic Number and Atomic Mass

Lesson 12 from the textbook was introduced with a brief review of atomic number and atomic mass.  Key learnings:

  • Atomic number = # of protons in one atom of a given element
  • Protons have a positive charge
  • Electrons have a negative charge
  • Neutral atoms have equal numbers of protons and electrons
  • Atomic mass = (# of protons) + (# of neutrons) in one atom of a given element
  • Neutrons have no charge

Example of Entry Task Notes:


Students then worked in pairs to complete the Lesson 12 Worksheet.  Students who need more practice with this lesson are encouraged to work through the Element Builder Gizmo.  See Mr. Swart for the instruction packet.  Successful completion of the packet will earn students one bonus point.

Homework for this evening:

  • Read Lesson 12 in the textbook.  Login via and enter your username and password:
    • Username: wahps****s-####### (**** = first 4 letters of your last name and ####### = student number).  Remember to include the dash between s and #.
    • Password: S-####### (the S must be capitalized)
  • Work through the homework problems at the end of Lesson 12 and then verify accuracy with the Lesson 12 Homework Answers.
  • Write notes for Lesson 12 on the Chapter 03 Notes handout.
  • Come to class tomorrow prepared to ask questions about anything of the homework problems from lesson 12 you did not understand.


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