Chemistry Unit 2: Atomic Structure 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?

Unit Essential Questions

  1. What experimental evidence led to the development of models of the atom?
  2. What changes were made to each model as questions were asked?
  3. How are the characteristics of elements attributed to the quantity, type, and nature of atoms?
  4. How do the combinations of the smallest atomic units affect the mass and charge of matter?
  5. What’s the difference between the mass of one atom and the average mass of many atoms?
  6. How do scientists make use of one another's work?
  7. How does new knowledge change our understanding of nature?
  8. What model of the atom is currently accepted by the scientific community? Why?
  9. How are the characteristics of elements attributed to the quantity, type, and nature of atoms?
  10. What properties of atoms favor the formation of ions?


  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
  • mass number
  • ion
  • isotope
  • proton
  • neutron
  • electron
  • nucleus
  • model
  • valence electron
  • photoelectric effect
  • orbital
  • quantum
  • wavelength
  • frequency
  • electromagnetic radiation
  • wave-particle nature
  • mole
  • molar mass
  • conservation
  • proportion
  • calculate
  • evidence
  • theory
  • law
  • claim
  • reasoning
  • convert
  • explain/explanation
  • question
  • relationship
  • interpret
  • impact
  • formulate
  • construct/construction
  • misconception

Students will know....

  • Terms:
    • Atom. Define it.
    • Use the atomic number, atomic mass, and mass number to find the number of protons, neutrons, and electrons in a neutral atom of a given element
    • Ions are charged atoms or groups of chemically bonded atoms. Ions form when atoms or group of chemically bonded atoms gain or lose electrons.
    • Electrons in the outer energy level of an atom are known as valence electrons. Core electrons are found in the inner energy levels and do not usually take part in chemical reactons.
    • Use numbers of subatomic particles present in an atom to define ion, isotope.
    • Explain the difference between relative atomic mass and atomic mass number.
  1. Symbols and names for 50 common elements, and their location on the periodic table
  2. Explain the significance of the findings in these experiments:
    1. Cathode Ray tube
    2. Oil Droplet
    3. Gold Foil
  3. Ions form when electrons are lost or gained.
  4. The periodic table described the arrangement of electrons in atoms long before scientists knew about atomic tructure, and still does today.
  5. Names and formulas of assigned monatomic and polyatomic ions.
  6. Conceptual and mathematical relationships betwen energy, light, and electrons
  7. Light has characteristics of both particles and waves
  8. When certain frequencies of light strifke a metal, electrons are emitted
  9. Electrons exist only in very specific energy states for atoms of each element
  10. Bohr's model of the hydrogen atom explained electron transition states.
  11. Electrons have wave-like properties
  12. The speed and position of an electron cannot be measured simultaneously.
  13. Orbitals indicate probably electron locations.
  14. Quantum numbers describe atomic orbitals.
  15. Electrons fill the lowest-energy orbitls first.
  16. Notation is used to indicate electron configurations.
  17. No electrons can occupy a higher-energy sublevel until the sublevel below it is filled.

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. Explain how isotopes of an element are similar and how they differ.
  10. Define model. Explain how scientists use models.
  11. Formulate 2 investigative questions about atomic structure that are not explained by Thomson's Plum Pudding Model or Rutherford's Solar System Model.
  12. Explain that three branches of knowledge that led to the construction of the currently accepted model of the atom.
  13. Explain the mathematical relationship among speed, wavelength, and frequency of electromagnetic radiation.
  14. Describe the role of Bunsen and Rydberg's work with atomic spectra in the modification of the atomic model.
  15. Discuss the dual wave-particle nature of light.
  16. Discuss the significance of the photoelectric effect and the line-emission spectrum of hydrogen to the development of the atomic model.
  17. Use mathematical equations including appropriate variables and constants, to demonstrate the relationship among wavelength, frequency, and energy of light.
  18. Describe the Bohr model of the hydrogen atom, and its shortcomings.
  19. Discuss Louis deBroglie's role in the developmemt of the quantum mechanical model of the atom.
  20. Compare and contrast Bohr's model and the quanum model of the atom.
  21. Discuss the dual wave-particle nature of light.
  22. Explain how the Heisenberg uncertainty principle aand the Schrodinger wave equation led to the idea of atomic orbitals.
  23. List the 4 quantum numbers and explain their significance.
  24. Relate the number of sublevels corresponding to each of an atom's main energy levels, the number of orbitals per sublevel, and the number of orbitals per main energy level.
  25. State common misconceptions people may have about the structure of atoms. Formulate an explanation of the quantum model.
  26. Calculate the relative atomic mass of an element, given percents and mass numbers of a set of its isotopes.
  27. Count the number and types of atoms in a chemical formula
  28. Find the molar mass of an element on the periodic table, or calculate the molar mass of a compound.
  29. Create conversion factors from molar masses and use them to convert between grams and moles.
Chapter 3.1 The Atom: From Philosophical Idea to Scientific Theory - Learning Targets
  • Three basic laws describe how matter behaves in chemical reactions. List and describe each.
  • List and explain or offer an example of each of the 5 statements that make up Dalton's Atomic Theory. Explain why this is a theory. What does the atomic theory explain?
  • Which statement in Dalton's Atomic Theory was modified after it was tested? Explain.
  • Use one of the laws explained by Dalton's Atomic Theory to write a response to Critical Thinking Question 3 on pg 67.
Chapter 3.2 The Structure of the Atom
  • Use a chart to track scientists, their experiments, their results, and the significance of the results for the model of the atom, and the limitations of each model. You will add more scientists and their work later.
    • JJ Thomson - cathode rays 1897; Robert Millkan - oil drop 1909; plum pudding model
    • Ernest Rutherford(geiger, Marsden) - gold foil and alpha particles 1911; beginning of solar system model
    • James Chadwick (not in text - what did he do?)
  • Describe the sizes and charges of subatomic particles
  • Use the periodic table to find charges on ions
Chapter 3.3 The Structure of the Atom
  • Explain the difference between an isotope and an ion of the same element.
  • Using a mathematical example, show how the atomic mass of an element found on the periodic table is calculated.
  • State Avogadro's number and explain how it is used to count toms, molecules, or other tiny particles.
  • Calculate the molar mass of an element and a compound.
  • Use Avogadro's number and the molar mass of a substance to describe the substance in terms of grams, moles, and number of particles. (this is a conversion factor calculation.)


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

Links - Atomic Structure

Links - calculations

Original Works

Daily Learning Activities
Day 16
Oct 25-26
  • Read Ch 3.1 and do a reading journal.
  • The atom, as a model
    • Inside the Atom - structure of the atom and subatomic particles
  • Discussion of the main ideas in the reading assignment Ch. 3 Section 1.
  • Review of the use of the terms law, theory, hypothesis in science.
  • How knowledge becomes theory: use of the terms law, theory, hypothesis, model in science.
  • Dalton's Atomic Theory - as a theory explaining a body of experimental evidence


  • Read, using your reading guide Ch 3 Section 2.
Day 17
Oct 27-28


  • Summarize Dalton, Thomson, Millikan, and Rutherford's work on the History of Atomic Structure Chart. Refer to Chapter 3, Section 2 and your notes/handouts for reference.
Day 18 Oct
31-Nov 1

Counting by Weighing - activity


  • Ch 3-3 reading
  • Pay very close attention to the calculation of average atomic mass.

Day 19
Nov 2-3

Atomic Structure, Part 1 and Counting Atoms

  • Discuss Counting by Weighing activity, and Calculations
  • Review atomic structure so far: Complete questions on Model 2-4 handout
  • Build on our understanding of this work to examine parts of an atom.
  • State the atomic number and mass number, and the number of protons and neutrons and electrons in an atom of any element using the periodic table
  • Explain the differences between isotopes of the same element.


  • Structure of the Periodic Table

Day 20 Nov 4 & 7

  • The atom, as a model
    • Use the model as we know it so far to make meaning of the periodic table
    • Use the model of the atom to detect patterns on the periodic table.
  • How ions form, and why this is important: See notes (also in What We Did in Class Today)
  • Your knowledge of the ions formed and the pattern made by ions on the periodic table will be very useful as you make meaning of the periodic table.
  • Development of a model for determining the number of valence electrons in an atom by its position on the periodic table. You now know 44 of the 66 ions we use frequently (the mobatomic ions), just by understanding the periodic table.
Day 21 Nov 8-9
  • Questions on isotopes, atomic numbers, atomic mass, mass numbers?
  • Atomic structure quiz
  • Questions on the ions you are learning?
  • Flame test lab - to see what Bunsen saw on our journey towards a model of the atom


  • Continue work on 1-6 (page 1 front and back) on Ion Study Guide, monatomic ions
Day 22
Nov 10 & 14
  • Ion check-in - how are you doing?
  • Old Dead Guys, Part 2: Bunsen, Rydberg,Planck, Einstein Bohr, deBroglie, Heisenberg, Schrödinger
  • What did they add to the model of the atom?


  • Continue work on 1-6 (page 1 front and back) on Ion Study Guide, monatomic ions

Day 23
Nov 15-16

  • Electron Configuration POGIL;
  • practice ion quiz


  • Continue work on 1-6 (page 1 front and back) on Ion Study Guide, monatomic ions

Day 24
Nov 17-18
  • Quiz - monatomic ions
  • Polyatomic ions
  • Atomic Structure and the Flame Test: More Old Dead Guys


Day 25
Nov 28-29

Electromagnetic Radiation and Energy

  • Ion Quiz 1
  • Old Dead Guys, Part 2: So where are the electrons really, and how do we know this?
  • Analysis of Flame Test Lab in terms of Bunsen and Rydberg's atomic spectra work leading to the Bohr Model.
  • Review Light problems and begin Planck's Constant problems
  • Relation to periodic table and practice
Day 26
Nov 30-Dec 1

Electrons in Atoms: Electron Configurations

  • Ion Quiz 2
  • Planck's Constant problems due
  • Revisit Electron Configuration POGIL
  • Complete the electron configuration periodic table until you recognize several patterns, both across a row and down a column.
Day 27
Dec 2 & 5
  • Ion Quiz 3
  • Catching up.....


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 1989-2016 L.C.Lee,


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