1. Conductivity Lab

2. Warm Up
1. Why is it not a good idea to take a hair dryer into the bathtub?
EQ: What is the difference between an ionic compound and a molecular compound?
HOT Q1: How can we distinguish between ionic and molecular compounds based on their conductivity?
HOT Q2: What are the properties of ionic compounds?
HOT Q3: What are the properties of molecular compounds?

3. Agenda Warm Up Agenda Quiz Conductivity Lab Exit Ticket
QUIZ MONDAY! (on nomenclature and properties of molecular vs. ionic compounds)
TEST WEDNESDAY!

4. Lab: Conductivity Date
Intro:
Purpose: To distinguish between ionic and molecular compounds based on their conductivity.
Hypothesis: I think molecular compounds do/do not conduct electricity, while ionic compounds do/do not conduct electricity.
Background info:
Conductivity: the ability of a substance to conduct electricity
Electricity : ______________________________________________

5. Materials: Methods: Conductivity probes
Salt, tap water, sugar, and distilled water
Methods:
Test samples of ionic compounds, molecular compounds, and solutions for electrical conductivity

6. Data:
Substance
Conductivity
Tap water
Distilled water
Distilled water with sugar
Sugar
Distilled water with salt
Salt
Analysis:
1. Which substances conducted the most electric current? Which substances conducted the least?

7. Discussion
Which substances did not conduct electricity in their solid form but did conduct electricity when they were dissolved in water?
Which substances did not conduct electricity either as a solid or dissolved?
The formula for sugar is C6H12O6 and the formula for salt is NaCl. Sugar is a molecular compound and salt is an ionic compound. Looking at the formula, are they made of metal elements, nonmetal elements or both? Based on this and your knowledge of their conductivity, what is the difference between ionic and molecular compounds?
Based on your knowledge of electricity, attempt to explain why sugar water will not conduct electricity as well as salt water. Use particle diagrams to support your answer.

8. Video: Dissociation of Salt

9. Electrolytes

10. Conclusion
1) What is the difference between distilled water and faucet water at the particle level? 2)What is the difference at the particle level between solid salt and salt dissolved in water? 3) What is the difference at the particle level between salt water and sugar water? The formula for sugar is C6H12O6 and the formula for salt is NaCl

11. Consensus Electricity is the free movement of charged particles
When ionic solids are melted or dissolved, oppositely charged ions are free to move and can conduct electricity
When molecular compounds are melted or dissolved, the molecules are electrically neutral and do not conduct electricity

12. MOLECULAR COMPOUNDS Properties -do NOT conduct electricity
-low melting pt. and boiling pt.
Basic structural unit
-building block: The molecule
-made of 2 or more nonmetal atoms bonded together
- weak attractions between molecules
Molecular compounds are made of two or more nonmetals bonded together.
Molecular compounds DO NOT break up into ions when they are melted and dissolved so they are poor conductors.

13. Molecular Compounds
Solid Dissolved/Melted

14. Ionic Compounds Properties
-generally have high melting pt. and boiling pt.
-conduct electricity when molten (melted) and dissolved (electrolytes).
Basic Structural Unit
-Formula Unit (FU)
ex: NaCl which is Na+ and Cl-
-As a solid many formula units
come together to form a crystal lattice.
-As a liquid they separate into ions, not
molecules or formula units.
NaCl crystal lattice

15. Ionic Compounds
Solid Dissolved/Melted

16. Crystal Lattice

17. Exit Ticket
1. What type of bonding is associated with compounds that have the following characteristics: •high melting points •conduct electricity in the molten state •solutions conduct electricity •normally crystalline solids at room temperature. A) covalent B) ionic C) hydrogen D) metallic