Part I: Atomic Structure – Instructional Unit
Unit Plan Title: Part I: Atomic Structure
Developed by: Ben Brown and Roberta Tanner
Academic Vocabulary: atom, nucleus, proton, electron,
neutron, atomic number, atomic mass, shells, ion,
isotope, periodic table
Grade Level: 9
Geophysical Lab
Science.
Length of lesson: One 95
minute period.
Essential Questions: What essential questions will focus this lesson?
1. How do subatomic particles combine to make an atom?
2. How can subatomic particles be used to identify an atom?
3. How has an understanding of atomic structure impacted science and engineering?
Link to NGSS standards for this lesson
Content and Skills: What will students learn and do?
Learn: The basic structure of the atom including sub-atomic particles, their charges and locations; using the
periodic table; how atomic number, name of element, and mass number are determined; meaning of a
neutral atom, positive and negative ions and their charges; shell structure for the Bohr atom; isotopes and
neutron/proton ratio for stability in the lighter atoms.
Do: Operate the iPad tablet. Use a period table to describe the atomic structure of different elements.
Link to Follow-up Lessons: What can be taught after this lesson?
Materials:
App: The iPad and the free app called “Nuclear” by Feel Great Publishing Limited. The app allows students to
build the first 54 atoms and can be reset for the next class of students using “settings” and “reset tutorial” or
“reset elements”.
Handouts: Atom Builder, Particle Cards (1-2 sheets/class), Extension: Building Atoms.
Pretest: Given a periodic table, have students draw a diagram showing the positions, names, and charges of
all of the particles in a Beryllium atom.
Engage:
Body Demo – to introduce terms and assess prior knowledge.
1) Preparation: Prepare one Particle Card (template provided) or slip of paper for each student. The card
will have either “proton”, “neutron”, or “electron” written on it.
2) Activity – Give one card (one particle) to each student.
a. Tell students the center of the room represents the center of an atom.
b. Ask students to find their place in the room based on the word on their card. They may talk to
each other as they move.
c. Once students have placed themselves in the room, ask as many questions from the list below
as seems reasonable. Because the next activity involves guided discovery, the teacher should
not answer these or any student questions at this time, nor should wrong answers be
corrected!
3) List of potential questions
a. Raise your hand if you are a proton … a neutron … an electron. Do any of you need to
relocate? Why? (Count and write the number of each on the board for later questions)
b. What is the charge on our atom? What do you think? How do you know?
c. What is the mass number of this atom? What do you think? How do you know?
d. Should any of you particles be moving? (Note to teacher: Nucleons vibrate, electrons “orbit”.
We will model the Bohr atom, so circles are fine.)
e. Do all of the electrons orbit in a single circle? (See if students have an understanding of shells
and maximum numbers of electrons in the inner 3 shells. Answer: 2, 8, 8.)
Note: If the class is self-correcting (after a few guiding questions), wonderful! If the class is confused and
can’t organize themselves correctly, tell them that today’s activity will help them understand the particles in
the atom, and then move on.
Explore: Students will use the iPad and the app called “Nuclear” by Feel Great Publishing Limited. If the iPad
is not available, alternative simulations for use on a computer can be found at
http://phet.colorado.edu/en/simulation/build-an-atom and http://www.camse.org/sims/builder/.
Handout: Atom Builder Handout (key available)
Timing: Give students 3-5 minutes to do the on-line tutorial and become familiar with the simulation before
they begin working on the handout. The activity will take about 45 minutes, but can be broken into 2 parts
(pages 1-2 and pages 3-4) with note taking between them.
Pedagogy: The structure of the lesson is discovery, so let students know they can find all answers on the app
and that this is an exploration. If they ask for answers to questions that are on the sheet, guide them to the
section of the app that will help them answer – do NOT answer for them! If they ask questions that are
outside the scope of the handout, you might first respond with “What do you think?” and have a discussion
rather than simply giving an answer. If students are working in pairs they should feel free to discuss their
findings with their partners.
Note: The mass number and atomic number positions in the app are different than on many periodic tables.
We suggest that you do not explain the difference until students use an actual periodic table during the
extend part of the lesson. By that time they should understand the difference between mass and atomic
numbers and should adapt quickly. When the periodic table is presented, the teacher might also explain why
the mass number is a decimal number (atoms of the same name exist with various numbers of neutrons).
Early finishers: During a discovery style lesson, some students will finish before others and some will not
finish at all. Early finishers might start on the Extend worksheet or if computers are available, play with the
PHET HTML5 simulation “Build an Atom” http://phet.colorado.edu/sims/html/build-an-atom/latest/build-anatom_en.html (works on iPad), or Java based simulations “Isotopes and atomic mass”.
http://phet.colorado.edu/en/simulation/isotopes-and-atomic-mass and “Build a molecule”
http://phet.colorado.edu/en/simulation/build-a-molecule.
Explain:
This section of the lesson could be straight lecture or copying notes from the transparency “Traditional
Notes”. A student-centered way to present notes (recommended) is explained below and has a transparency
outline titled “Discuss and Write Notes”. The teacher can use “Traditional Notes” as a key during the
discussion, to ensure that all ideas are discussed. If the app is split into two sections, have students close
iPads and while they take notes after each section.
“Discuss and Write Notes” involves a whole class summary discussion of the exploration part of the lesson,
guided by an outline that matches the exploration. There are several ways to do this, but try to involve
students in developing the answers. Encourage them to use the handout they just completed. One
suggestion follows:
1) Teacher introduces the next topic and asks student pairs to discuss a definition or answer (about 30
seconds).
2) Ask students to share with the class. Encourage more than one answer by asking other students
“what did you think?” or “what part of that was confusing” or “what did you discuss”.
a. Use questions to extend the topic or deepen the thinking.
b. Avoid saying “right” after one student answers, because that will shut down deeper thinking.
3) Students either write their own notes on the concept or state the definition they will write.
a. If students write their own definitions, ask several students to share what they have written
and have students correct their notes as needed.
b. If the class needs help knowing how to correct the notes they have written, the teacher could
write and project important points (that were brought up by the class).
4) Lead students in constructing Bohr model examples in their notes (guided practice – suggestions on
the last page of the notes).
During the notes (page 2), pass out the Periodic Table and discuss the different locations of atomic and
mass numbers as compared to the app.
Extend: Building Atoms worksheet - students answer questions and draw the Bohr model of several
elements. Check students’ answers as they work on the worksheet. Potassium is a good atom for a quick
check because it will have one electron in the outer shell.
Evaluate the learning goal: Given the periodic table the student will be able to answer questions about the
particles in various elements, and draw diagrams to show the location, charge on, and number of subatomic
particles in atoms and ions.
Posttest:
1) Given a periodic table, students draw a Bohr model of the most common Sulfur ion with charge 1+.
a. Use different symbols for each type of particle and
b. make a key identifying the name, charge, and symbol used for each particle.
2) Grading Rubric is below.
Far Below Standard
Students’ Bohr model has
major errors such as no labels
or missing or incorrect charges
on particles, particles and
electron shells are drawn in
random or grossly incorrect
positions or are missing.
Approaching Standard
Students draw a Bohr model
of the Sulfur ion with all
particles labeled with the
correct charge but not all
particles in their correct
position or electron shells are
incorrect OR the ion is
correctly drawn and labeled
but has two or more errors,
(see “meeting standards”).
Meeting Standard
Students draw a Bohr model
of the Sulfur ion, all particles
labeled, the correct charges in
their correct positions,
electrons in their correct
shells, but with one error, for
example a neutral atom
instead of an ion, an extra
electron instead of lack of an
electron, or equal numbers of
protons and neutrons.
Exceeding Standard
Students correctly draw a
Bohr model of the most
common Sulfur ion with a
charge of 1+, including the
correct number of electrons in
each shell. Key with correct
name and charge should be
provided.
Modifications: Extra time if needed. Introduction to Periodic Table worksheet for extra practice.
NGSS Standard(s): What standards will provide the focus for this unit?
This activity covers the following high school standards (DCIs accented in bold) and enables students to develop a solid foundation so
the standards can be fully addressed in later lessons.
Disciplinary Core Ideas

HS-PS1-1. Use the periodic table as a model to predict (the relative properties of elements based on) the patterns of
electrons in the outermost energy level of atoms. [Clarification Statement: Examples of properties that could be predicted from patterns could


include reactivity of metals, types of bonds formed, numbers of bonds formed, and reactions with oxygen.] [Assessment Boundary: Assessment is limited to
main group elements. Assessment does not include quantitative understanding of ionization energy beyond relative trends.]
HS-PS1-2. (Construct and revise an explanation for the outcome of a simple chemical reaction based on the) outermost
electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties.
[Clarification Statement: Examples of chemical reactions could include the reaction of sodium and chlorine, of carbon and oxygen, or of carbon and hydrogen.]
[Assessment Boundary: Assessment is limited to chemical reactions involving main group elements and combustion reactions.]
HS-PS1-7. Use mathematical representations to support the claim that atoms, and therefore mass, are conserved
during a chemical reaction. [Clarification Statement: Emphasis is on using mathematical ideas to communicate the proportional relationships between
masses of atoms in the reactants and the products, and the translation of these relationships to the macroscopic scale using the mole as the conversion from
the atomic to the macroscopic scale. Emphasis is on assessing students’ use of mathematical thinking and not on memorization and rote application of problem
solving techniques.] [Assessment Boundary: Assessment does not include complex chemical reactions.]
Science and Engineering Practices

Developing and Using Models

Develop a model based on evidence to illustrate the relationships between systems or between components of a
system. Use a model to predict the relationships between systems or between components of a system.
Constructing Explanations and Designing Solutions Construct and revise an explanation based on valid and reliable evidence obtained from
a variety of sources (including students’ own investigations, models, theories, simulations, peer review) and the assumption that theories and laws that describe
the natural world operate today as they did in the past and will continue to do so in the future.
Cross-cutting Concepts

Patterns Different patterns may be observed at each of the scales at which a system is studied and can provide evidence for causality

in explanations of
phenomena.
Scientific Knowledge Assumes an Order and Consistency in Natural Systems
Science assumes the universe is a vast single
system in which basic laws are consistent.
Follow-up Lessons: What can be taught after this lesson?
HS-PS1-1 Ionic and covalent bonds (using what was learned in this lesson about shell structure and
allowed number of electrons in each shell).
HS-PS1-1 Reasons metals are so reactive
HS-PS1-1 Reactions with oxygen
HS-PS1-2 Chemical reactions (predicting outcomes based on valence electrons)
HS-PS1-7 Mathematical representations (conservation of atomic number and mass number during
chemical reactions – stoichiometry)
HS-PS1-8 Nuclear processes (students will understand the typical proton/neutron ratio and will be
able to make sense of nuclear processes such as radiation, fission, and fusion)