MiddleSchoolPortal/Turning Points in Science: Atomic Theory

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Turning Points in Science: Atomic Theory - Introduction

This is the third publication in our series called Turning Points in Science, which highlights the history and nature of science. The first publication covered the topic of germ theory and the second the Copernican revolution. The third in the series, Atomic Theory, highlights human thinking and theorizing regarding the structure and nature of matter.

Several themes that appeared in the first two publications are seen in Atomic Theory as well. First, the Copernican revolution conveyed two important reasons for a study of historical events in science: (1) Because it underscores and makes more real the nature of science — that science progresses when the findings of one person become the stepping stone for another to advance human understanding, and (2) because these turning points impacted society and culture in irreversible ways.

Second, the methods of science vary with the discipline. The methods in physical science are probably the closest to conceptions of science methods students may hold. In physical science, fairly certain conclusions can be drawn from well-controlled laboratory investigations because confounding variables are largely eliminated. Thus, the hypothetical-deductive model of science is often played out as predicted.



Third, like the previous two publications in the series, this publication aims to facilitate student mastery of the Science as Inquiry and History and Nature of Science content standards; this time in the context of elucidation of atomic theory. Thus, some of the Physical Science content standards are touched upon too.

Finally, as in the previous publications, avoiding the temptation of verification exercises remains a priority. Rather, allow students to make their own "discoveries," to interpret their observations, to make logical inferences, and to derive supported conclusions. In the context of atomic theory, students will engage in simulation and demonstration activities as well as some laboratory exercises from which they can make some inferences regarding the structure of matter.

In this publication, our first resources begin with the ancient Greeks, particularly Democritus, who is credited with giving us the word atom, from atomos, meaning indivisible. Interestingly, even then there were at least two competing theories of the nature of matter. There was Democritus' idea of atoms and there was Empedocles' idea of the four elements: earth, air, fire, and water.

Empedocles' theory was endorsed by Aristotle and endured for centuries due to his authority rather than any convincing empirical evidence. Then, as with germ theory, several individuals over time made observations contributing to an evolution of the atomic theory, which has become quite detailed. Resources provided here intend to help teachers help students gain knowledge and understanding of this course of human thinking, i.e., scientific habits of mind and how knowledge of the atom enables further progress in science.

In Germ Theory the background information provided research articles on naive conceptions, how to conduct inquiry teaching, and a video segment on the nature of scientific theory. Those resources are equally helpful here, but are not repeated here. The Background Information section in this publication provides resources regarding the many individuals across time whose work impacted the evolution of the atomic theory. Resources that might be considered more cultural and historical then scientific are included, since science does not progress in a vacuum, but within the cultural parameters of a society.

The Lessons and Activities are meant to facilitate student understanding of the context, the emergence, and the impact of the atomic theory, touching on the National Science Education Standards of History and Nature of Science, to Physical Science, and Science as Inquiry.

We refer you to the National Science Teachers Association's excellent position statement on Scientific Inquiry for guidance regarding how teachers can conduct inquiry teaching and what teachers can expect from students.

Background Information for Teachers

Teachers have little time to get acquainted with the context and background of much of the content they are required to teach. We hope these resources save you time while providing you with helpful information that fills this information gap. Resources in this section will acquaint you first with relationships historically significant scientific breakthroughs and the nature of science. After that resources focus on important figures in the field, the nature of their work, and the impacts of their work on world views of the nature and structure of matter.

First we direct you to a resource that encompasses all of the Atomic Theory: the history, the nature of science and the content. The NSDL Strand Map Service provides concept maps illustrating connections between concepts and across grade levels. An image of the middle grades (6-8) only part of the Chemical Revolution map appears below. This map is one of nine under the heading Historical Perspectives. Below that is an image of the grades 6-8 section of the Scientific Communities map, one of seven found under the heading Nature of Science. Clicking on a concept within the maps will show NSDL resources relevant to the concept, as well as information about related AAAS Project 2061 Benchmarks and National Science Education Standards. Move the pink box in the lower right hand corner of the page to see the grades 6-8 learning goals. You may also be interested in Atoms and Molecules.

The Particle Adventure: What Is Fundamental? Although this tutorial is designed for high school students, it can serve as an excellent review for middle school teachers. It covers the history of particle physics, discussing, for example, Rutherford's experiment and findings as well how physicists study small particles and how we know what we know about atoms and the structure of matter. Parts of the tutorial are appropriate for sharing directly with middle school students.

John Dalton This short biography is accompanied by an image of Dalton and includes the three tenets of his atomic theory. The link to Berzelius illustrates how atomic theory was useful in identifying ions and ionic compounds.

J.J. Thompson: The Nobel Prize in Physics 1906 A brief biography of the man whose original study of cathode rays culminated in the discovery of the electron.

Ernest Rutherford: The Nobel Prize in Chemistry 1908 Rutherford’s research and many discoveries about the nature of the inner structure of the atom are described in this biography.

Rutherford and Bohr Describe Atomic Structure 1913 This page is from the PBS series A Science Odyssey: People and Discoveries. It describes Bohr's contribution to theories of the atom and its relationship to others' theories, such as Rutherford's. Links to relevant pages are provided. An image of Bohr's research notes is included.

James Chadwick This is an easy-to-read biography of Chadwick, who discovered the neutron.

Lessons and Activities

With your knowledge of the history of atomic theory, you are ready to assist students in gaining accurate conceptions of the structure of matter and appreciation for how we know what we know about the atom. The lessons and activities in this section are designed to allow student insight into past and present perceptions of the structure of matter.

Early Atomic Understanding A brief timeline covers the major ancient Greeks and their beliefs about the nature of matter. Students can be asked: Who seemed to have the most imaginative ideas? The most probable? On what were these ideas based? How did their methods of science compare to current methods of science? Why?

Guess What? This hands-on activity for upper elementary and middle school students simulates how scientists make inferences regarding the structure of matter not directly observed.

Strange Matter This interactive page zooms from the outside of a beverage can down to the level of aluminum atoms. As the image zooms, a schematic reference scale shows the level of magnification the image represents.

Matter: Atoms, Molecules and States of Matter This lesson introduces atomic theory from Democritus to John Dalton and reviews Dalton’s four basic theories on matter. It is the first lesson in a series on atomic structure.

Building on Biographies - Bringing Real-Life Stories into Your Curriculum! One strategy to give students a personal perspective on the scientists who contributed to modern atomic theory is to have students investigate these persons through biographies and autobiographies. This article from Education World presents ways around student conceptions of biographies as boring and highlights ways to integrate language arts with other disciplines by having students engage with biographies. For example, they can build a "biography box" or write a "people poem." If students are allowed to work in pairs to investigate a given scientist, the activity is not only more pleasant for the student but also allows for greater learning potential. Students will be bouncing ideas off each other as they construct their own understanding of their scientist's life, work and contributions to science and society.

Latest Science News from the New York Times

NYT > Atoms

<p>An atom is the smallest amount possible of an element such as carbon or silver. The original Greek word means "indivisible," but atoms turn out to be divisible into smaller components: a dense nucleus of protons and neutrons surrounded by a wispy cloud of electrons. A neutral atom consists of equal numbers of protons and neutrons. The lightest atom is hydrogen, which consists of one proton and one electron.</p>

NYT > Electrons

<p>With a mass of 9.1 x 10<sup>-31</sup> kilograms, the electron is the lightest fundamental particle that carries an electric charge. In an atom, a cloud of negatively charged electrons surrounds the positively charged nucleus of protons and neutrons. </p>

NYT > Protons

<p>A proton is a positively charged subatomic particle found in the nuclei of atoms. The number of protons in an atomic nucleus defines what type of atom it is. For example, a carbon atom has 12 protons in the nucleus, and a silver atom has 47 protons.</p>

NYT > Neutrons

<p>A neutron is a subatomic particle with no electric charge found in the nuclei of atoms. Within an atom, a neutron is stable. However, a single neutron by itself is not, typically decaying after about 10 minutes into a proton, an electron and an anti-neutrino.</p>

NYT > Physics

News about Physics, including commentary and archival articles published in The New York Times.

SMARTR: Virtual Learning Experiences for Students

Visit our student site SMARTR to find related science-focused virtual learning experiences for your students! The SMARTR learning experiences were designed both for and by middle school aged students. Students from around the country participated in every stage of SMARTR’s development and each of the learning experiences includes multimedia content including videos, simulations, games and virtual activities.


The FunWorks Visit the FunWorks STEM career website to learn more about a variety of science-related careers (click on the Science link at the bottom of the home page).

National Science Education Standards

Concepts of this publication align with the following content standards of the National Science Education Standards.

History and Nature of Science: Content Standard G

Science as a Human Endeavor

  • Women and men of various social and ethnic backgrounds — and with diverse interests, talents, qualities, and motivations — engage in the activities of science, engineering, and related fields such as the health professions. Some scientists work in teams, and some work alone, but all communicate extensively with others.
  • Science requires different abilities, depending on such factors as the field of study and type of inquiry. Science is very much a human endeavor, and the work of science relies on basic human qualities, such as reasoning, insight, energy, skill, and creativity — as well as on scientific habits of mind, such as intellectual honesty, tolerance of ambiguity, skepticism, and openness to new ideas.

Nature of Science

  • Scientists formulate and test their explanations of nature using observation, experiments, and theoretical and mathematical models. Although all scientific ideas are tentative and subject to change and improvement in principle, for most major ideas in science, there is much experimental and observational confirmation. Those ideas are not likely to change greatly in the future. Scientists do and have changed their ideas about nature when they encounter new experimental evidence that does not match their existing explanations.
  • In areas where active research is being pursued and in which there is not a great deal of experimental or observational evidence and understanding, it is normal for scientists to differ with one another about the interpretation of the evidence or theory being considered. Different scientists might publish conflicting experimental results or might draw different conclusions from the same data. Ideally, scientists acknowledge such conflict and work towards finding evidence that will resolve their disagreement.
  • It is part of scientific inquiry to evaluate the results of scientific investigations, experiments, observations, theoretical models, and the explanations proposed by other scientists. Evaluation includes reviewing the experimental procedures, examining the evidence, identifying faulty reasoning, pointing out statements that go beyond the evidence, and suggesting alternative explanations for the same observations. Although scientists may disagree about explanations of phenomena, about interpretations of data, or about the value of rival theories, they do agree that questioning, response to criticism, and open communication are integral to the process of science. As scientific knowledge evolves, major disagreements are eventually resolved through such interactions between scientists.

History of Science

  • Many individuals have contributed to the traditions of science. Studying some of these individuals provides further understanding of scientific inquiry, science as a human endeavor, the nature of science, and the relationships between science and society.
  • Tracing the history of science can show how difficult it was for scientific innovators to break through the accepted ideas of their time to reach the conclusions that we currently take for granted.

Science as Inquiry: Content Standard A

Abilities Necessary To Do Scientific Inquiry

  • Develop descriptions, explanations, predictions, and models using evidence. Students should base their explanation on what they observed, and as they develop cognitive skills, they should be able to differentiate explanation from description — providing causes for effects and establishing relationships based on evidence and logical argument. This standard requires a subject matter knowledge base so the students can effectively conduct investigations, because developing explanations establishes connections between the content of science and the contexts within which students develop new knowledge.
  • Think critically and logically to make the relationships between evidence and explanations. Thinking critically about evidence includes deciding what evidence should be used and accounting for anomalous data. Specifically, students should be able to review data from a simple experiment, summarize the data, and form a logical argument about the cause-and-effect relationships in the experiment. Students should begin to state some explanations in terms of the relationship between two or more variables.
  • Recognize and analyze alternative explanations and predictions. Students should develop the ability to listen to and respect the explanations proposed by other students. They should remain open to and acknowledge different ideas and explanations, be able to accept the skepticism of others, and consider alternative explanations.
  • Communicate scientific procedures and explanations. With practice, students should become competent at communicating experimental methods, following instructions, describing observations, summarizing the results of other groups, and telling other students about investigations and explanations.

Read the entire National Science Education Standards online for free or register to download the free PDF. The content standards are found in Chapter 6.

Author and Copyright

Mary LeFever is a resource specialist for the Middle School Portal 2: Math & Science Pathways project, a doctoral candidate in science education at Ohio State University, and presently teaches introductory biology at a Columbus, Ohio local high school. She has taught middle school and high school science and is an adjunct instructor of biology and natural sciences at Columbus State Community College.

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Copyright December 2007 - The Ohio State University. Last updated September 20, 2010. This material is based upon work supported by the National Science Foundation under Grant No. 0424671 and since September 1, 2009 Grant No. 0840824. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.