Technicolor Atoms The Flame Tests PreLab Read the

Technicolor Atoms The Flame Tests

Pre-Lab • Read the lab description on page 86. • Make a data table with the headings below: • List the substances and their formulas in the table from the materials list on pg 86.

Chem Catalyst • These drawings are models that show solid copper, solid copper chloride, and aqueous copper chloride as collections of atoms. 1. Describe each model. 2. What is similar about each model? What is different?

Safety • Legs and feet covered • Hair tied up • Move with caution • Monitor bunsen burners carefully • Do not cross-contaminate Q-Tips

Go Do Lab

Team Analysis 1. Group the substances based on the flame colors produced. 2. What patterns do you notice in the groupings? 3. Predict the flame color for a substance called strontium sulfate. Explain your reasoning. 4. What evidence do you have that atoms of certain elements produce a flame of a specific color? 5. Can a flame test be used to identify a metal atom in a compound? What about a nonmetal atom? Explain.

Discussion • Which part of the compound seems to be producing the colors? What’s the evidence? • How can you use the flame test to identify elements in a substance? • What are some good uses for this phenomenon?

Notes • It is the metal in the compounds which causes the colored flame • The flame test can be used to determine what metals in are in an unknown compound. • Metals are used in fireworks and other applications for color

More Notes: Explaining the Colored Light • Electrons can move within the atom. • Heat from the flame excites the electrons, causing them to jump to an energy level farther from the nucleus. • When the electrons “fall” back to their original energy level, energy is released as colored light. Sodium Atom The different colors of light released are evidence that electrons move in different “energy shells”.

Getting Specific • If you pass the colored light through a prism or a diffraction grating, the color will get separated into specific wavelengths of light. This is an emission spectrum • All elements have an emission spectrum, and it is unique to that element – like a finger print.

Homework • Lesson 17 • Read pages 87 -90 • Questions 1 -2, 5 -7, 9 -11