Chemistry Unit 2: Atoms and the Periodic Table, Part 1


  • Describe the experimental evidence for historical models of the atom.
  • Explain the role of experimental evidence in our understandings of the natural world.
  • Explain how experimental evidence shaped the development of the currently accepted model of the atom.
  • Use Avodagro’s number and what we know about the mass of atoms and different elements to do useful calculations about chemicals.

Course Essential Questions

  • How can we study things that are to small to see?1
  • How might scientific inquiry be used to investigation the natural world?
  • How can I use my experience in chemistry to learn to think and communicate clearly, logically, and critically in preparation for college and a career?
  • How can I best assess my own learning and progress?


  1. Experimental evidence leads to the development of models and/or theories as possible explanations.
  2. Scientific models are refined as questions about the model lead to further investigation.
  3. Atomic structure is responsible for the physical and chemical properties of elements.
  4. Atoms are counted by weighing them.
  5. Atoms of the same element may have different numbers of neutrons (isotopes) and electrons (ions) but not protons.
  6. The Quantum Mechanical Model is the currently accepted explanation of atomic structure based on many different kinds of empirical evidence.
  7. Atomic structure is responsible for the physical and chemical properties of elements, as in the formation of ions, and both inter- and intramolecular forces.

Prior Knowledge

  1. Unit Conversions and Dimensional Analysis (we will review)
  2. Names and symbols of 50 common elements

Prior Skills

  1. Make and use conversion factors in dimensional analysis
  2. Assign appropriate variables to quantities in a lab calculation or story problem.
  3. Use scientific notation in mathematical calculations
  4. Solve a 3-variable equation for any one variable

Terms: Bricks

Terms: Mortar
  • atom
  • atomic number
  • atomic mass
  • average relative atomic mass
  • mass number
  • proton
  • neutron
  • electron
  • nucleus
  • ion
  • isotope
  • model
  • mole
  • molar mass
  • valence electron
  • core electron
  • conservation
  • proportion
  • evidence
  • theory
  • law
  • claim
  • reasoning
  • explain/explanation
  • interpret
  • calculate
  • impact
  • formulate
  • construct/construction
  • misconception
  • question
  • relationship

Students will know....

  1. How to count particles (atoms and molecules and formula units) by weighing them.
  2. The three basic laws that describe how matter behaves in chemical reactions.
  3. The statements in Dalton's Atomic Theory that explain the 3 laws (above)
  4. Explain the significance of the findings in these experiments:
    1. Cathode Ray tube
    2. Oil Droplet
    3. Gold Foil
  5. Relative sizes and charges of subatomic particles
  6. Ions form when electrons are lost or gained.
  7. The periodic table described the arrangement of electrons in atoms long before scientists knew about atomic tructure, and still does today.
  8. Names and formulas of assigned monatomic and polyatomic ions.
  9. Relationships among isotopes of the same element
  10. THe difference between ions and isotopes
  11. Avogadro's number, and how and when to use it

Students will be able to....

  1. Define theory. Explain why the Atomic Theory is a theory.
  2. Explain the laws of conservation of mass, definite proportions, and multiple proportions.
  3. Summarize the 5 essential points of Dalton's atomic theory.
  4. Explain the relationship between Dalton's atomic theory and the laws of conservation of mass, definite proportions, and multiple proportions.
  5. Interpret the experiments of Thomson, Millikan, and Rutherford and explain how their results impacted the formation of an early atomic model.
  6. Formulate 2 investigative questions about atomic structure that are not explained by the Plum Pudding Model.
  7. Describe Rutherford' work and explain how he used the results to formulate the Solar System Model.
  8. Explain what every atom of a given element has in common.
  9. Use the periodic table to find charges on ions
  10. Explain how isotopes of an element are similar and how they differ.
  11. Define model. Explain how scientists use models.
  12. Formulate 2 investigative questions about atomic structure that are not explained by Thomson's Plum Pudding Model or Rutherford's Solar System Model.
  13. State common misconceptions people may have about the structure of atoms. Formulate an explanation of the quantum model.
  14. Calculate the relative atomic mass of an element, given percents and mass numbers of a set of its isotopes.
  15. Count the number and types of atoms in a chemical formula
  16. Find the molar mass of an element on the periodic table, or calculate the molar mass of a compound.
  17. Create conversion factors from molar masses and use them to convert between grams and moles.


  • Inside the Atom, Model 1
  • Structure of the Periodic Table

Links - Atomic Structure

Links - calculations

Original Works

Next Generation Science Standards:
Disciplinary Core Ideas:
NGSS Science and Engineering Practices:
SEP 2 Developing and using models

NGSS Crosscutting Concepts: Scale, Proportion Quantity, Energy and Matter

Using Mathematics and Computational Thinking, Planning and Carrying Out Investigations

Creative Commons License
This work by Luann Christensen Lee is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Copyright 1989-2017 L.C.Lee,


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