Teacher Portal

Properties of Matter: Investigation 1 –

PostLab

 

 

 

 

 

 

 

ZERO-IN

Italicized font represents information to be shared orally or physically completed with the students at this time.

The non-italicized font represents additional information included to support the teacher’s understanding of the content being introduced within the CELL.

ANALYZE IT

  • After student groups have investigated and recorded various physical properties, including the masses and volumes of the unknown substances, discuss the impact of their observations and measurements on the investigation.
  • Instruct students to complete the Analysis Questions in their SDRs then discuss them as a class. Use the suggested responses below to guide students’ answers.

Note: Questions marked with a triangle (∆) are included to enrich students’ understanding. These questions do not appear in students’ SDRs but should be used as additional discussion points during the PostLab.

  • Do any of the substances share similar properties? Student answers will vary. Samples B and F are gray or silver in color. Samples A and D appear to have a similar texture and color. Samples C. and E are both white.
  • Compare the physical properties of the different samples. Can you determine which samples are elements and which are compounds? If so, how? If not, why? Student answers will vary. It is likely that students will not have been able to discern the difference between substances that are elements and those that are compounds because many of the properties such as color, texture, visual appearance, mass, and volume are similar for many of the substances. Based on previous knowledge, students may have looked for properties that would differentiate elements from compounds. Often the difference between elements and compounds is described as elements as substances that cannot be broken down by ordinary means. However, this is not a property that students explored in their investigation.
  • Is it possible to determine whether any of the unknown substances contain the same elements? If so, how? If not, why? Students will likely indicate that without previous knowledge of the properties of all elements and compounds or samples of known elements or compounds at their disposal, a definite identification is not possible. However, students should begin to suggest that comparison to known properties would be advantageous, and should also use previous knowledge to begin making hypotheses. For example, students should be able to suggest that substances have textures or colors similar to aluminum foil, sugar, chalk, or copper, or other substances they have encountered.
  • Can you determine whether any of the unknown substances contain the same elements? If so, how? If not, why? No. We do not have information from our investigation such as a molecular formula for each substance, nor have we compared each substance’s properties against those of known elements or compounds. We could hypothesize that substances with similar colors or textures have similar elemental composition. However, we cannot determine conclusively which substances contain the same elements.
  • What other types of information may be helpful in determining the identity of the substances and elemental composition of the substances? Student answers will vary. Allow students to provide a variety of suggestions. As students put forth several possibilities, work to guide an inclusion of the following properties: density, solubility in water, and chemical reactivity. These are properties that students will investigate in later portions of the Core Experience Learning Lab.

Note: Students should use their data and the information from the Backgrounds to answer the questions in the Analysis section.

GET FOCUSED

Instruct students to complete the Focus Questions in their SDRs then discuss them as a class. Use the suggested responses below to guide students’ answers.

  • Can you tell the difference between an element and a compound by measuring mass and volume? Explain your answer. Student answers will vary. It is likely that students will not have been able to discern the difference between substances that are elements and those that are compounds because many of the properties such as color, texture, visual appearance, mass, and volume are similar for many of the substances. Based on previous knowledge, students may have looked for properties that would differentiate elements from compounds. Often the difference between elements and compounds is described as elements as substances that cannot be broken down by ordinary means. However, this is not a property that students explored in their investigation.
  • Can you determine the identity of an unknown substance by observing its mass and volume? Explain your answer. Students will likely indicate that without previous knowledge of the properties of all elements and compounds or samples of known elements or compounds at their disposal, a definite identification using just mass and volume is not possible. However, students should begin to suggest that comparison to known properties would be advantageous, and should also use previous knowledge to begin making hypotheses. For example, students should be able to suggest that substances have textures or colors similar to aluminum foil, sugar, chalk, or copper, or other substances they have encountered.