About Chemical Reactions at the SRC

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About Chemical Reactions

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Like all our Science Reasoning Center activities, Chemical Reactions provides information about a phenomenon, experiment, or data presentation to answer questions. This information is accessible by tapping on the small thumbnails found on the bottom right of every question. However, it may be considerably easier to have a printed copy of this information or to display the information in a separate browser window. You can access this information from this page.

The Standards
The Chemical Reactions is an NGSS-inspired task that includes five activities that guide students through the task of predicting the product of a simple reaction between two elements by using an understanding of how the location of an element on the Periodic Table (and thus, the number of valence shell electrons) affects the chemistry of that element. Students also learn how to balance the chemical equation using coefficients and conducting an atom count to insure it is balanced. Each activity involves a different type of skill or understanding. Collectively, the five activities were designed to address the following NGSS performance expectation:

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 patternsof chemical properties.

As a whole, the questions in this task address a wide collection of disciplinary core idea (DCI), crosscutting concepts (CCC), and science and engineering practices (SEP). There are 76 multi-part questions organized into 20 Question Groups and spread across the five activities. Each question is either a 2D or (preferably) a 3D question. That is, the task of answering the question requires that the student utilize at least two of the three dimensions of the NGSS science standards - a DCI, a CCC, and/or an SEP.

The following DCI, SEPs, and CCCs are addressed at some point within Chemical Reactions:

DCI: PS1.A: Structure and Properties of Matter

The periodic table orders elements horizontally by the number of protons in the atom’s nucleus and places those with similar chemical properties in columns. The repeating patterns of this table reflect patterns of outer electron states.

DCI: PS1.B: Chemical Reactions

The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

SEP 2.3: Developing and Using Models
Develop, revise, and/or use a model based on evidence to illustrate and/or predict the relationships between systems or between components of a system.

SEP 2.4: Developing and Using Models
Develop and/or use multiple types of models to provide mechanistic accounts and/or predict phenomena, and move flexibly between model types based on merits and limitations.

SEP 6.2: 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.

CCC 1.1: 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.

CCC 5.2: Energy and Matter
The total amount of energy and matter in closed systems is conserved.

CCC 7.1: Stability and Change
Much of science deals with constructing explanations of how things change and how they remain stable.

Here is our NGSS-based analysis of each individual activity of the Chemical Reactions Science Reasoning task. The core ideas, crosscutting concepts, and science and engineering practices that we reference in our analysis are numbered for convenience. You can cross-reference the specific notations that we have used with the listings found on the following pages:

Science and Engineering Practices || Crosscutting Concepts

Disclaimer: The standards are not our original work. We are simply including them here for convenience (and because we have referenced the by number). The standards are the property of the Next Generation Science Standards.

Part 1: The Periodic Table

This activity consists of 12 forced-choice questions organized into four Question Groups. Students are presented a paragraph that describes patterns associated with the number of outer shell electrons and the tendency to gain, lose, or share electrons in order to obtain an octet (or duet). Students complete the paragraph by filling in the blanks with missing words or phrases selected from a bank. Once all blanks are filled in and evaluated, they are told how many correct blanks they have (but not which blanks are correct). They have unlimited tries to correct their answers in order to make the paragraph accurate. Students earn the Trophy for this activity once they accurately complete a paragraph for each of the four Question Groups.

NGSS Claim Statement: Predict the manner in which two elements would combine and the bonds that they would form based on an understanding of the patterns that are observed in their electronegativity and the number of outer shell electrons in their atoms.

Target DCI(s)	Target SEP(s)	Target CCC(s)
Structure and Properties of Matter PS1.A The periodic table orders elements horizontally by the number of protons in the atom’s nucleus and places those with similar chemical properties in columns. The repeating patterns of this table reflect patterns of outer electron states.	Constructing Explanations and Designing Solutions SEP 6.2 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. Developing and Using Models SEP 2.4 Develop and/or use multiple types of models to provide mechanistic accounts and/or predict phenomena, and move flexibly between model types based on merits and limitations.	Patterns CCC 1.1 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. Stability and Change CCC 7.1 Much of science deals with constructing explanations of how things change and how they remain stable.

Part 2: Matching Pairs

This activity consists of 16 forced-choice questions organized into four Question Groups. Students are presented with a diagram of the outer shell electrons for four pairs of main group elements. They are also presented formulas for four binary compounds. They must match the formulae to the diagrams. Students earn the Trophy for this activity once they demonstrate mastery on all four Question Groups.

NGSS Claim Statement: Predict the manner in which two elements would combine based on an understanding of the patterns that are observed in their electronegativity and the number of outer shell electrons in their atoms.

Target DCI(s)	Target SEP(s)	Target CCC(s)
Structure and Properties of Matter PS1.A The periodic table orders elements horizontally by the number of protons in the atom’s nucleus and places those with similar chemical properties in columns. The repeating patterns of this table reflect patterns of outer electron states.	Developing and Using Models SEP 2.3 Use a model based on evidence to predict the relationships between systems or between components of a system.	Patterns CCC 1.1 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. Stability and Change CCC 7.1 Much of science deals with constructing explanations of how things change and how they remain stable.

Part 3: Compound Formation

This activity consists of 16 forced-choice questions organized into four Question Groups. Students are presented with the elemental symbol and electronegativity value of two main group elements. They must answer 10 questions regarding the set of two elements - the type of bonds they form, the number of valence electrons in each atom, the number of electrons gained or lost by each atom to become a stable ion, the charge on each ion, the ratio at which the ions combine to form an ionic compound, and the formula of the resulting compound. Students earn the Trophy for this activity once they demonstrate mastery on all four Question Groups.

NGSS Claim Statement: Predict the manner in which two elements would combine and the bonds that they would form based on an understanding of the patterns that are observed in their electronegativity and the number of outer shell electrons in their atoms.

Target DCI(s)	Target SEP(s)	Target CCC(s)
Structure and Properties of Matter PS1.A The periodic table orders elements horizontally by the number of protons in the atom’s nucleus and places those with similar chemical properties in columns. The repeating patterns of this table reflect patterns of outer electron states. .	Developing and Using Models SEP 2.4 Develop and/or use multiple types of models to provide mechanistic accounts and/or predict phenomena, and move flexibly between model types based on merits and limitations.	Patterns CCC 1.1 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. Stability and Change CCC 7.1 Much of science deals with constructing explanations of how things change and how they remain stable.

Part 4: Predicting and Explaining

This activity consists of 16 forced-choice questions organized into four Question Groups. Students are presented the formulas for the two reactants. There are four potential explanations for how they bond (ionic vs. covalent) and the formula that would result from their bonding. They must inspect details of each explanation and identify the explanation that accurately describes the rationale for both the type of bonding and the resulting formula. Students earn the Trophy for this activity once they demonstrate mastery on all four Question Groups.

NGSS Claim Statement: Identify the proper explanation for the manner in which two elements combine to form a compound based on an understanding of their location in the periodic table and the patterns associated with their electronegativity value and the number of outer shell electrons.

Target DCI(s)	Target SEP(s)	Target CCC(s)
Structure and Properties of Matter PS1.A The periodic table orders elements horizontally by the number of protons in the atom’s nucleus and places those with similar chemical properties in columns. The repeating patterns of this table reflect patterns of outer electron states. Chemical Reactions PS1.B The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.	Constructing Explanations and Designing Solutions SEP 6.2 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. Developing and Using Models SEP 2.4 Develop and/or use multiple types of models to provide mechanistic accounts and/or predict phenomena, and move flexibly between model types based on merits and limitations.	Patterns CCC 1.1 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. Stability and Change CCC 7.1 Much of science deals with constructing explanations of how things change and how they remain stable.

Part 5: Balance It

This activity consists of 16 forced-choice questions organized into four Question Groups. Students are provided the formulas for the reactants of a simple synthesis reaction. Students must predict the chemical formula of the product. Then they balance the chemical equation using coefficients. Finally, they conduct an atom count to show that atoms are conserved. Feedback is provided with each of the three steps (formula identification, coefficients, atom count); students must correct their answers before they move on to the next step. Students earn the Trophy for this activity once they demonstrate mastery on all four Question Groups.

NGSS Claim Statement: Predict the product produced by the synthesis reaction of two elements and balance the chemical equation using an understanding that atoms are conserved in a chemical reaction.

Target DCI(s)	Target SEP(s)	Target CCC(s)
Structure and Properties of Matter PS1.A The periodic table orders elements horizontally by the number of protons in the atom’s nucleus and places those with similar chemical properties in columns. The repeating patterns of this table reflect patterns of outer electron states. Chemical Reactions PS1.B The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.	Developing and Using Models SEP 2.3 Uuse a model based on evidence to predict the relationships between systems or between components of a system.	Energy and Matter CCC 5.2 The total amount of energy and matter in closed systems is conserved.

View: Science and Engineering Practices || Crosscutting Concepts

Also see:

Chemical Reactions Activity || Teacher Preview Pages (Task Tracker Teachers Only)

About the Science Reasoning Center || SRC and Task Tracker