About the Science Reasoning Center

About Melting Points and Boiling Points

Highly Recommended

Like all our Science Reasoning Center activities, the completion of Melting Points and Boiling Points relies on the use of provided 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 Melting Points and Boiling Points activity is an NGSS-inspired task that consists of five parts. Each of the five parts seeks to highlight the relationship between the bulk scale properties of melting point and boiling point for varying substances to the strength of the intermolecular forces between particles. Each part of the activity involves a different type of skill or understanding. Collectively, the five parts were designed to address the following NGSS performance expectation:

HS-PS1-3:

Plan and conduct an investigation to gather evidenceto compare the structure of substances at the bulk scaleto infer the strength of electrical forces between particles.

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 56 multiple choice questions organized into 17 Question Groups and spread across the five parts. 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 Melting Points and Boiling Points:

DCI:  PS1.A: Structure and Properties of Matter

• The structure and interactions of matter at the bulk scale are determined by electrical forces within and between atoms.
• Each atom has a charged substructure consisting of a nucleus, which is made of protons and neutrons, surrounded by electrons.

DCI:  PS1.B: Types of Interactions

• Attraction and repulsion between electric charges at the atomic scale explain the structure, properties, and transformations of matter, as well as the contact forces between material objects. 

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 4.5: Analyzing and Interpreting Data 

Evaluate the impact of new data on a working explanation and/or model of a proposed process or system.

SEP 6.3:  Constructing Explanations and Designing Solutions 

Apply scientific ideas, principles, and/or evidence to provide an explanation of phenomena and solve design problems, taking into account possible unanticipated effects.

SEP 7.4:  Engaging in Argument from Evidence

Construct, use, and/or present an oral and written argument or counter-arguments based on data and evidence.

SEP 7.5:  Engaging in Argument from Evidence

Make and defend a claim based on evidence about the natural world or the effectiveness of a design solution that reflects scientific knowledge, and student-generated evidence.

CCC 1.1: Patterns

Patterns of performance of designed systems can be analyzed and interpreted to reengineer and improve the system.

CCC 2.1: Cause and Effect

Empirical evidence is required to differentiate between cause and correlation and make claims about specific causes and effects.

CCC 6.2:  Structure and Function

The functions and properties of natural and designed objects and systems can be inferred from their overall structure, the way their components are shaped and used, and the molecular substructures of its various materials.

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 Melting Points and Boiling Points 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:

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: Paragraph Completion

This activity involves a paragraph-completion exercise. Students use a word/phrase bank to select missing words and phrases in order to complete a paragraph containing 7 blanks. Once students complete their paragraph, they can submit their answers for evaluation and feedback. On each answer submission, they are told the number of correct blanks but not told which blanks are correct. Students have an unlimited number of opportunities to correct their answers. Students earn the Trophy for the activity once they correctly complete both paragraphs.

NGSS Claim Statement: Apply concepts associated withintermolecular forces and the boiling processto explainthe changes of matter from liquid to gas.

Part 2: Halogen Boiling Points

This activity consists of 16 multiple choice or multiple select questions organized into four Question Groups. Students are presented a table of data displaying the melting points of four halogens. Students use the melting point values to infer information about the strength of intermolecular forces and they use the trends in these values to make and defend a claim regarding the dependency of the intermolecular forces upon the molecule size. Students earn the Trophy for this activity once they demonstrate mastery on all four Question Groups. 

NGSS Claim Statement: Use patterns associated with a bulk scale processto develop a model ofintermolecular forcesand to explain how such forces impact boiling points.

Part 3: Melting Point of Metal Halides

This activity consists of 16 multiple choice or multiple select questions organized into four Question Groups. Students are presented with data displaying the melting points for halides of four alkali metals. They look for trends in the data and identify appropriate claim-evidence-reasoning statements that emerge from the data. Students earn the Trophy for this activity once they demonstrate mastery on all four Question Groups. 

NGSS Claim Statement: Use patterns associated with the melting points of metal halidesto make and defend a claim that relates melting point data tothe strength of interparticle forces.

Part 4: Boiling Points of Non-Metal Hydrides

This activity consists of 16 multiple choice or multiple select questions organized into four Question Groups. Students are presented data showing the melting points of the hydrides of Group 14, 15, and 16 non-metals (and metalloids) as a function of the period. They identify the trends for the groups and for the periods, noting any exceptions to the general rule. They also relate the bulk scale property to the strength of the intermolecular forces. Students earn the Trophy for this activity once they demonstrate mastery on all four Question Groups. 

NGSS Claim Statement: Use patterns associated with the boiling points of non-metal hydridesto make and defend a claim that relates boiling point data tothe strength of intermolecular forces.

Part 5: Breaking the Trend

This activity consists of 16 multiple choice or multiple select questions organized into four Question Groups. Students continue their investigation of the boiling points of the non-metal hydrides. But in this activity, students identify breaks to the customary trend and provide an explanation in terms of intermolecular forces. Students earn the Trophy for this activity once they demonstrate mastery on all four Question Groups. 

NGSS Claim Statement: Analyze boiling point data to determine patterns and to relate the patterns tointermolecular forcesand to explain unanticipated effects by the introduction ofless-commonly observed intermolecular forces.

Complementary and Similar Resources

The following resources at The Physics Classroom website complement the Melting Points and Boiling Points Science Reasoning Activity. Teachers may find them useful for supporting students and/or as components of lesson plans and unit plans.

Concept Builders, Chemistry

Concept Builders, Chemistry - Intermolecular Forces (coming soon)

Concept Builders, Fluids - Properties of Matter

Science Reasoning Center - Investigating Intermolecular Forces