Kate Drummond
Abstract
With students’ graphic representations, collaborative research, and using knowledge of the periodic table to make element predictions, our periodic table lab shifted from rote learning and disinterest to critical thinking, synthesis, and engagement.
In our department’s periodic table unit,The Atom Part 2: Electrons and the Periodic Table, formerly students learned about periodic table law and how it was created through lectures and reading assignments. In the unit’s lab, names of the elements were given to the students and students observed the elements’ properties to see differences among metals, non-metals and metalloids.There was no problem to solve, no elements to identify, no discovery, nor application of the periodic law as a model to predict locations of elements and identify them. In addition, kids never seemed as interested as I thought they would be.Though students certainly preferred the hands-on experience of the lab, to teacher-directed lecture or solving equations, they did not seem engaged in the learning process.
I wanted students to use the periodic table as it is intended to be used, to make predictions about elements and their properties, not just learn about the table for the sake of memorizing facts about elements.
I wanted students to use the periodic table as it is intended to be used, to make predictions about elements and their properties, not just learn about the periodic table for the sake of memorizing facts about elements. In collaboration with my chemistry teaching colleague, the periodic table unit has been transformed. Students now graphically represent a mini-periodic table that contains diagrams of electron configurations, engage in a collaborative research activity, and make element predictions. With these three new learning activities and supports involving students’ collaboration, teacher as coach, students’ presentations, and peer feedback – students are guided to learn about the periodic table through discovery, and actively use it.
Periodic Table Unit
STANDARD #1: Developing and Using Models : “Students will be able to develop and use different types of models (diagrams, physical replicas, mathematical representations, analogies, and/or computer simulations) to represent a system, to aid in the development of questions and explanations, to generate data, and/or to communicate ideas to others.” – Maine Supervisory Administrative District (MSAD) 54 Science Graduation Standard #1. (For Standard #1 Success Criteria, see Appendix B).
The Periodic Table Unit is provided in seven, 80-minute class periods, with five periods prior to the lab, and two periods for the lab. In a pre-assessment, students diagram an atom’s structure (see Figure 1). The unit’s post assessment is a test on atomic structure with multiple choice, true/false, fill-in-the-blank, short answer, and constructed response questions (see Appendix A).
The unit begins with an interactive simulation, Build an Atom, which allows students to move protons, neutrons, and electrons into an “atom” and see how the changing atomic structure corresponds to the element’s placement on the periodic table.The simulation allows for visualization of the otherwise nonsensical numbers, associated with each element. Build an Atom and other simulations for science and math are provided free-of-charge from PhET, an initiative of the University of Colorado, Boulder.
Figure 1. Student’s pre-assessment.
Students’ Periodic Table Mini-Versions. Students progress to interpreting the periodic table and sketching their own atomic models of the elements. Eventually, they create a mini-version of the periodic table, filling out and arranging eighteen element cards containing models of atoms (see Figure 2).
From this visual model, students begin to identify patterns in electron arrangement within the vertical (groups/families) and horizontal (periods).
Figure 2. Student’s periodic table mini-version.
Collaborative Research. Following creating their periodic table mini-versions, students engage in collaborative research, with each group sharing their findings with the other groups. Small groups of students are assigned one family of elements to research and discuss with their group members.The students study differences and similarities in the properties of the elements, in their assigned element family, and relate these properties to the structure of the atoms. Each group creates a slide show with their findings.The groups then share what they have learned, with the rest of the class. As small groups share, the rest of the class fills in notes about each vertical group of the periodic table, and answers reflection questions.Through the combination of all groups’ presentations, the entire class learns about all the element families.
Presentations. The research groups’ presentations are short and informal. Presentation guidelines are a checklist of basic features for effective presentation, and the requirement that everyone in the group must play a role or present, at least one slide. To set a standard for presentation quality, I model presentation skills and show exemplars from past classes.The presenting group is in a horseshoe shape around the screen or whiteboard. Presenting group members have a choice to stand or sit. Presentations typically run about five minutes long, with me as timekeeper. My classes tend to do a lot of whole class sharing throughout the year, so students get more confident over time.
Peer Feedback
Students fill out a checklist for their peers and provide verbal positive feedback at the end of each presentation.Students tend to have helpful feedback for one another. Occasionally, depending on the class dynamics, the feedback will be repetitive. Most of the time, when students give peer feedback, those receiving the feedback already have an idea what the suggestions will be.
Peer feedback is kept short and expectations clear. Since students are often uncomfortable giving “cool” feedback, I often don’t require it. Using peer feedback for positive reinforcement, I have found, is a great way to build trust and create a positive, supportive group dynamic.
Atomic radius and electronegativity. To further fine-tune students’ understanding of concepts related to the periodic table, the final lesson before lab challenges students to use atomic radius and electronegativity values for each element, to explain differences in how elements react.This exercise demonstrates to students why calcium is more reactive than magnesium, even though both elements are in the Alkaline Earth Family.
Students watch videos about two of the most reactive elements, calcium and magnesium. They then use what they have learned about periodic trends regarding atomic radius and electronegativity, to write and verbally share an explanation for why these two elements, from these specific locations on the table, are considered the most reactive.
Atomic radius and electronegativity are identified as important vocabulary for the unit, so students have worked with their definitions in previous assignments. This activity requires students to apply the definitions, in their explanations. Students have reference periodic tables in their textbook and online, for example in Ptable that contain the atomic radius and electronegativity values for all the elements.
Atomic Radius and Electronegativity
Effects on Elements
Electronegativity measures the strength of attraction a positively charged nucleus has for its negatively charged outer layer of electrons (called valence electrons). As atoms of the elements increase in their numbers of protons, neutrons and electrons, the radius increases to accommodate more particles. This increase in radius causes the valence electrons to move further and further away from the protons.
As a result of this increase in radius, the force of attraction between the protons and valence electrons decreases. For example, the element fluorine has a small atomic radius because it has only nine protons and two layers of electrons. Therefore, the protons can “pull” the electrons close to the nucleus. The element chlorine, which is one row below fluorine, on the periodic table, and in the same family, has three layers of electrons. Therefore, chlorine has a slightly larger nucleus and a weaker electronegativity than fluorine. Furthermore, the increase in layers of electrons between the nucleus and the valence shells in chlorine shields the outer electrons from the attractive force of the protons.
This activity is done in small groups of two-three students. Students discuss ideas, share them verbally, and then write them down. I move between groups and ask students to elaborate or to clarify their ideas. As I do this, I can identify and challenge misunderstandings and confusion. At this point in the unit, students have enough background knowledge to begin using the periodic table as it was intended: to make predictions about elements.
Collaboration
A Framework for K12 Science Education states:
“…science is fundamentally a social enterprise, and scientific knowledge advances through collaboration and in the context of a social system with well-developed norms … In short, scientists constitute a community whose members work together to build a body of evidence and devise and test theories” (National Research Council, 2006, p. 27).
In the overall unit and the lab, students engage in collaboration. Collaborative groups are two or three students, who work together throughout the quarter. Students collaborating is intentional and allows students to use an authentic scientific practice.Collaboration with partners encourages individuals to talk through ideas and problem solve together, during the sense-making process. Students are required to sketch and explain their ideas within their group, among groups, and in front of the whole class.
I use a few different strategies to help students plan the workload, when working together in small groups. One strategy is to assign roles, another is to use group “planning surveys” in which group members make decisions about their work and assign tasks to one another. Another scaffold I use is to give each group a list of tasks, to equitably assign to group members.
Students update and revise their ideas based on feedback from peers and me. Shared Google Slides for creating presentations about families of elements, Google Jamboard frames for sharing and comparing lab data, and erasable whiteboards for sketching atomic models are tools that make feedback and revision easy, so they are used frequently throughout the unit to aid in collaboration.
Perhaps most importantly, upon completion of class activities, lab groups are called upon to share and discuss answers to reflection questions, using erasable whiteboards.These whiteboard report-outs require both lab partners to engage in creating a visual and communicating to the whole class an accurate, complete answer.
Forming groups. At the start of each quarter, new lab groups are assigned using the survey data for guidance.For the partner or partners students will have for lab and non-lab activities, students fill out a confidential survey to let me know with whom they work well and whether they have had a history of conflict with anyone in class.Then, I use this information, as well as my own observations to make lab groups.
Group member conflict. My instructions about how to handle possible group member conflict, including lab partner conflict, occur at the beginning of the year when I set behavior expectations with my classes. I instruct students to speak with me, privately, about problems or conflicts that arise, so we can brainstorm possible solutions together. This strategy has been used successfully by students 100% of the time, when a problem occurs. In addition, conflict is prevented because of groups having been formed, taking into account students confidential survey information regarding with whom they work well, and whether they have a history of conflict with anyone in the class.
Lab
Our lab begins with a whole class, problem-solving, brainstorming activity. I pose the following questions to the class:
What do we know about the properties of families of elements on the table?
Where are the metals, nonmetals, metalloids?
Where are the most reactive metals and nonmetals? Why?
What elements or groups of elements can we eliminate as options? Why?
How many nonmetals on the periodic table are solids? What do you know about them?
Working through the problem-solving process together this way, practices some important problem-solving skills that can be applied throughout life: identifying what is known before you start and using process of elimination to narrow the scope of the problem.
I write the students’ ideas on the front whiteboard, where I leave them for reference. As we answer these questions together, lab groups use erasable whiteboard markers to cross out elements on a laminated periodic table, thus narrowing down the options and making the problem seem more solvable. Working through the problem-solving process together this way, practices some important problem-solving skills that can be applied throughout life: identifying what is known before you start and using process of elimination to narrow the scope of the problem.
Synthesis. The lab’s culminating activity is students identifying elements, based on the elements’ properties. At this point, based on students’ knowledge and using critical thinking, the students can make accurate predictions. The students are given nine elements’ properties, without the elements’ names. Students must predict each of the nine elements by its properties. By observing the properties of the nine elements and using periodic law – on the periodic table there are repeating patterns in properties of the elements – students identify which elements they were given.
Since there are 118 elements to choose from, students are easily overwhelmed by the prospect of identifying which nine elements they were given for the lab. I guide them through a series of process of elimination steps, using what they’ve learned about periodic law. For example, I ask the class: “Which groups and periods on the periodic table do we know, we do not have as part of the lab?”
Since students know I would not give them radioactive elements, they can eliminate any elements with atomic numbers greater than 82. It is also easy for students to eliminate vertical column 18 since all the group 18 elements are colorless, odorless, non-reactive gases. Students’ confidence grows as they understand how to use process of elimination – and periodic law, together, to substantially narrow down the options.
By the time students reach the end of the unit, they have more knowledge, skill, and confidence for solving scientific problems.
From here, I give students time to work with their lab partner as I rotate around to each lab group and challenge thinking or answer clarifying questions. By the end of class, I ask lab groups to report out their identifications. Most of the time, they are correct. Sometimes there are two similar elements whose identification are switched, offering an opportunity for whole class problem solving.
My students now can predict properties of unknown elements. Along with the unit’s overall learning progression, simply keeping the names of the elements hidden and asking students to apply their knowledge of the Periodic Table to identify them, achieved this goal. With the unit’s adjustments, the experience for my students became less about observing the elements for the sake of simple exposure and more about engaging in what Framework for K12 Science Education (2016) advocates; engaging in cognitive, social, and physical practices that are foundational to science, instead of learning about them secondhand. By the time students reach the end of the unit, they have more knowledge, skill, and confidence for solving scientific problems.
Reflections
I wanted to evolve the periodic table lab from a simple observational experience with elements, to what Russian chemistry professor, Mendeleev, who developed the first periodic table intended: to predict properties of unknown elements.
The shift from teaching students to memorize facts in science class, to creating authentic experiences for students to practice science, is simply a more effective model of instruction.
The shift from teaching students to memorize facts in science class, to creating authentic experiences for students to practice science is simply a more effective model of instruction. When I am successful at implementing problem-solving processes in my lessons, my students seem happy and engaged. When I observe them working out a problem together, I notice that they behave as if they are playing. They smile, they joke, they try and fail, they exclaim with excitement, and ask for more time to work on the task. They are playing the role of scientists, and experiencing a sense of flow that occurs when you are so engaged and challenged with an activity that time seems to disappear. Graduating scientifically literate, capable students who enjoy science is imperative as we seek solutions to existential crises, such as climate change or sixth mass extinction.
The task of identifying elements can feel overwhelming without proper support and structure from the teacher. My practice during the periodic table lab has evolved into providing structure, giving students plenty of think time, and sprinkling timely clues throughout the process, to keep student interest and motivation high. I am in the role of coach and facilitator of learning, rather than the source of knowledge. However, I choreograph clues, so though students are challenged, they are not confounded by the activity.
Though the evolution of the periodic table lab and unit has increased student engagement and academic rigor and put students in the role of scientist, as intended by the Next Generation Science Standards (see Appendix C), it will forever be a work in progress. Teaching kids the skill of scientific modeling while simultaneously helping them understand and remember science content is a tricky task. I continue to work on making the learning goals and outcomes clearer for students. It has taken me 20 years of practice to develop the skills, knowledge, and confidence to facilitate active, problem-solving learning, and I am still learning. Much of what I have learned has come from professional development, and strong support from mentors and teacher collaborators. A key strategy for me was to find both teacher and scientist mentors who could help me understand and use the science practices myself.Teachers cannot be successful in isolation. Like scientists, they need collaboration to be part of their daily practice. Not only does teacher collaboration make improvement more efficient and effective, it provides mental and emotion support for practitioners, in a demanding human-centered field.
The authenticity of the periodic table lab task encourages mutual respect between the teacher and student, through the inherent message of confidence it sends. It communicates to students that they are capable problem solvers and appeals to their sense of independence and desire to be seen as adults. Asking students to solve authentic problems is a strategy for increased engagement in learning. By its very nature, authenticity in education demonstrates respect for students.
References
National Research Council. (2012). A framework for K-12 science education: Practices, crosscutting
concepts and core ideas.The National Academies Press. https://doi.org/10.17226/13165
National Research Council. (2006) America’s lab report: Investigations in high school science. The
National Academies Press. https://doi.org/10.17226/11311
Appendix A
Post-Unit Assessment
Part 1: Predicting Relative Properties of an Element
| Name of element | |
| Atomic number | |
| Element Symbol | |
| Group | |
| Period | |
| Metal/Nonmetal, or metalloid | |
| # of valence electrons | |
| Gain or Lose to fulfill the Octet Rule? | |
| # of energy levels | |
| Atomic radius (include value & tell if low, med., high) | |
| Electronegativity (High/low/none) |
Part 2: Explaining the Properties
You will use the bold terms and their values from your table as evidence to support the claim that your element is highly, moderately, or non-reactive.
For your evidence and reasoning write one combined paragraph (evidence and reasoning do NOT need to be separated) that:
(1) states the properties you previously identified (include all of the bold properties)
(2) define the properties and explain relationships between them, and
(3) clearly applies periodic trends to explain the reactivity of your element.
Part 3: Predicting & Explaining a Reaction
- Write a claim identifying an element that will react with your element. (Fill in the blank space with the appropriate words.
- What is the evidence that supports these two elements reacting? Make a bulleted list in the boxes provided.
- Explain your reasoning behind these two elements reacting using specific reactivity rule(s) as your scientific principle(s).
Part 4: Comparing the Outcome of 2 Reactions
Your teacher will assign a second element to react with original element in Part 1. Compare the reaction you described in Part 3 with this new reaction. Explain the difference in strength of the reaction using (at least) electronegativity and valence electrons.
- Claim: The reaction between _________ and _______ will likely be weaker or stronger (circle one) than the reaction described in part 3.
- What is the evidence that supports your claim? Make a bulleted list in the box provided.
- Explain your reasoning behind using this evidence to support your claim in the box provided.
Appendix B
Science Graduation Standard # 1: Developing and Using Models, Science, Maine Supervisory Administrative District (MSAD) Performance Indicator and Success Criteria
| Performance Indicator | 1 – Emerging | 2 – Developing | 3 – Proficient | 4 – Exceeds |
| Students will be able to 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. (11) HS-PS1-1 | I can describe the atomic structure of a given element based on its location on the periodic table. | I can describe the organizing principles, collectively known as periodic law, used to develop the periodic table. | I can 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. | I can use the periodic table as a model to predict which elements will react with one another, using scientific principles to explain my prediction. In addition to meeting the content area expectation at a proficient level, a student will earn a four by demonstrating proficiency with more complex content, using more complex taxonomy, or applying their learning in a real-world context. |
Appendix C
Kate Drummond is Chemistry and Environmental Science Teacher and Eco Team/ Outing Club Advisor at Skowhegan Area High School, Skowhegan, Maine. Kate Drummond can be reached at kdrummond@msad54.org.