Using properties to identify ionic and molecular compounds electricity generation in california


This activity is designed for students to test the physical properties of their choice to help them group the chemicals into ionic and covalent compounds categories. The students will write procedures for five different tests in which they will perform in which the teacher will approve of. The students will construct data tables with different compounds and the qualitative tests performed. From this information students will analyze their results to determine whether the compounds or mixtures are covalent or molecular compounds. Some of the skills students will do: observing, safe and clean lab practices, different waste disposal, repeat testing, defend their choices with oral discussions, and answering higher order questions. The key concept for students to learn in this activity is being able to determine what physical properties exist in an ionic or a molecular compound. Students will have to know terms of ionic compound, ionic bond, covalent bond and molecular compound. Context for Use

Each team member: In your ChemJournal write the procedure you will need to follow to test your chemicals. Plus, you need to decide which chemicals you want to test so you can form a high quality analysis and conclusion. Please separate the different procedures in your writing. Procedures must be approved before you can begin any testing… ANY TESTING!!!!

NOTE: Any paint thinner mixtures must be disposed in the "Paint Thinner Waste" Container in the hood. All benzoic acid & camphor waste must be placed in garbage can in front of the classroom with the garbage bag. All other mixtures may be flushed down the drain with water.

– An ionic compound is a compound that has an ionic bond. An Ionic bond is a type of chemical bond that involves a metal and a non-metal ion. The bond is formed by an attraction between tow oppositely charged ions. It is a bond where the electron(s) are transferred from one atom to another

a) In your conclusion discuss in writing ALL of the evidence (of all 5 tests). Then after reading the information about compounds, conclude with your team if each compound is ionic or covalent, or is it more in between. Document this information in the last column of your data table. Then (in your conclusion) compare your findings for each compound with what you now know about the ionic vs. covalent nature of each compound. Make sure this information is clear in your conclusion.

I’ve always had my students do a variation of this lab where I tell them what properties they will test and how to test them. This is inquiry so they will find the properties, which are common, and test them. The brainstorming discussions will help me direct the class into testing good quality physical properties. For guiding students, if necessary, tell the students to refer back to chapters about different types of matter or the Periodic Table trends to get students to think about: odor, melting point, electronegativity, Lewis-dot structures, boiling point, hardness, volatility (measure by odor), water solubility, alcohol or oil solubility and conductivity. If necessary, give containers of paint thinner, camphor, salt to each group to help them think of physical properties to test.

When testing students should list the equipment they will use in their tests, like test tubes, small beakers, spot plates, Bunsen burners with hoses, crucibles, etc. For testing, many of our schools don’t have the equipment but there are other great alternatives. Boiling point would be very hard to measure with the volatility of paint thinner, and the extreme temperatures of all compounds—steer students away from the boiling point. Melting point would not be impossible without proper equipment, use a crucible and measure the amount of time it takes to melt (if it does). The longer the time period means the higher the melting point. Volatility is measured by odor. The particles in a volatile compound must be held together by weaker forces so that some can break away and travel through the air to our noses. Hardness is measured by how malleable or brittle a compound is with a hammer and board. Conductivity my students have experience with conductivity during the periodic table unit. Conductivity can be measured with a meter or a homemade circuit.

Wait until all the data has been collected and students categorize their data before handing them the definitions of ionic and covalent bonds and also ionic and molecular compounds then they can discuss all their evidence and write it in their conclusion.