Elements - Metals, Nonmetals and Metalloids
Summary
In this activity, students will investigate several properties of the given elements and decide whether each element is a metal, non-metal or a metalloid. They will examine the appearance of the given samples and note the color, luster and form. Using a hammer, they will determine if it is brittle or malleable. They will test for electrical conductivity and the reactivity of each sample with hydrochloric acid and copper (II) chloride solution.
CollapseLearning Goals
From this activity, students will understand that every element is classified as a metal, nonmetal or a metalloid (semimetal) based on its individual properties. They will be able to classify an element as a metal, nonmetal or metalloid based on experimental observations of physical and chemical properties. This activity promotes the students' skills of observation, questioning, critical thinking and data analysis. The key concepts that the students will review during this activity are that metals have luster, they are malleable, are good conductors of electricity, react with acids and other aqueous solutions. Some of the vocabulary words that are reviewed by the students through this activity are luster, brittle, malleable, ductile, electrical conductor and insulator.
Context for Use
Resource Type
Activity: Lab Activity
Grade Level
High School (9-12)
Lesson Format:
This is a lab activity.
Time needed:
One class period
Materials:
Conductivity apparatus
Small hammers
Well plates
Element samples
Concept Knowledge:
Atomic structure of elements
Physical and chemical properties of metals, nonmetals and metalloids
Description and Teaching Materials
The students will form small lab groups of two or three members.
After I review the difference between physical and chemical properties, and the characteristics of metals, nonmetals and metalloids, the student groups will get samples in seven vials which have been coded with letters 'a' to 'g'. The samples the student groups get are carbon (pencil lead works), pieces of magnesium ribbon, silicon lumps, sulfur lumps, iron filings, and pieces of mossy zinc. The students have to group the samples under the categories of metals, nonmetals or metalloids. They will look at the appearance of the given sample to see if it has luster or is dull. They will use the hammer to test if the sample is brittle or malleable.
They will use the conductivity tester to see if the sample conducts electricity. Then they will test for the reactivity of the samples with 0.5M hydrochloric acid and 0.1M copper (II) chloride solution. They will take a small portion of the given samples in a well plate. To each sample, 15 to 20 drops of the acid solution will be added and they will look for any reaction (change ) happening like bubbles of hydrogen gas coming out. With copper (II) chloride which is a blue colored solution, they will be looking for color change of the liquid and of the sample.
The student groups will then make a data table to compare the observations for the given samples. They will discuss their findings in their own small groups and group the samples under two categories based on their physical and chemical properties and find which elements could fit into either of the groups and why. They will arrange the samples into metals, nonmetals and metalloids. The groups will then present their findings to the class and discuss how they arrived at their findings.
As a class we will group the elements under the three groups after discussing the criteria for assigning elements to groups.
After I review the difference between physical and chemical properties, and the characteristics of metals, nonmetals and metalloids, the student groups will get samples in seven vials which have been coded with letters 'a' to 'g'. The samples the student groups get are carbon (pencil lead works), pieces of magnesium ribbon, silicon lumps, sulfur lumps, iron filings, and pieces of mossy zinc. The students have to group the samples under the categories of metals, nonmetals or metalloids. They will look at the appearance of the given sample to see if it has luster or is dull. They will use the hammer to test if the sample is brittle or malleable.
They will use the conductivity tester to see if the sample conducts electricity. Then they will test for the reactivity of the samples with 0.5M hydrochloric acid and 0.1M copper (II) chloride solution. They will take a small portion of the given samples in a well plate. To each sample, 15 to 20 drops of the acid solution will be added and they will look for any reaction (change ) happening like bubbles of hydrogen gas coming out. With copper (II) chloride which is a blue colored solution, they will be looking for color change of the liquid and of the sample.
The student groups will then make a data table to compare the observations for the given samples. They will discuss their findings in their own small groups and group the samples under two categories based on their physical and chemical properties and find which elements could fit into either of the groups and why. They will arrange the samples into metals, nonmetals and metalloids. The groups will then present their findings to the class and discuss how they arrived at their findings.
As a class we will group the elements under the three groups after discussing the criteria for assigning elements to groups.
Teaching Notes and Tips
Students should wear safety goggles through out the lab activity. I use the conductivity tester from Flinn Scientific. If you do not have one, a simple tester can be constructed.
(Katz, D. and Wills, C., Journal Of Chemical Education, 1994, p.330) Forceps should be used to handle the element samples. I also review the process for using acids safely.
The only issue we had was with carbon. The student groups classified magnesium, zinc, iron and tin as metals; sulfur as nonmetal and silicon and carbon as metalloids. Carbon conducts electricity and does not have the characteristic luster. We need to consider the other properties like it is brittle, does not react with the two liquids to put carbon along with sulfur as a nonmetal.
(Katz, D. and Wills, C., Journal Of Chemical Education, 1994, p.330) Forceps should be used to handle the element samples. I also review the process for using acids safely.
The only issue we had was with carbon. The student groups classified magnesium, zinc, iron and tin as metals; sulfur as nonmetal and silicon and carbon as metalloids. Carbon conducts electricity and does not have the characteristic luster. We need to consider the other properties like it is brittle, does not react with the two liquids to put carbon along with sulfur as a nonmetal.
Assessment
I use the data table and their grouping of the given samples into three categories for assessment. Evaluation of student classification is done based on student observations, not necessarily what the actual sample is. Student - student discussions and group to group discussions are also used for evaluation.
Also, I give them a Venn diagram with two circles to compare the properties of metals, nonmetals and metalloids. I assign points for the completed Venn diagram. Members of each group get the same points.
Also, I give them a Venn diagram with two circles to compare the properties of metals, nonmetals and metalloids. I assign points for the completed Venn diagram. Members of each group get the same points.
Standards
II.A.1 - Structure of matter
I.B.1 - Scientific Inquiry
I.B.1 - Scientific Inquiry