Flame Test Lab

Pre-AP Mr. Drost Pre-Lab Questions

1. What are the alkali metal elements? Where are they located on the periodic table?

2. What are alkaline earth metal elements? Where are they located on the periodic table? Background Info When elements are heated to high temperatures, some of their electrons are excited to higher energy levels. These excited electrons can then fall back to lower energy levels, releasing the excess energy in packages of light called photons, or light quanta. The color of the emitted light depends on its energy. Blue light is more energetic than red light. When heated, each element emits a characteristic pattern of light energies which is useful for identifying the element. The characteristic colors of light produced when substances are heated in the flame of a gas burner are the basis of flame tests for several elements. In this experiment, you will perform flame tests for several metallic elements. Then you will identify an element from its flame test. Based on this information, please make notes for use in your lab report. Safety & Materials

• Safety • Materials – Wear goggles – Bunsen Burners – Use caution when using – Toothpicks presoaked in the Bunsen Burner solutions – Tie back long hair & do not – Chemical solutions: wear loose clothing • Sodium chloride • Calcium chloride • Strontium chloride • Potassium chloride • Barium chloride • Copper chloride • Lithium chloride • Unknown Procedure

1. Carefully light Bunsen Burner as instructed. 2. Grasp one presoaked toothpick with forceps. 3. Insert the chemically soaked toothpick into the hottest part of the flame. 4. Observe the flame color during the first 5-10 seconds of burning and record your observations. 5. Discard the expended toothpick. 6. Repeat steps 2-4 at each station until complete. Data/Observations Metal Ion Flame Color

Sodium (Na+)

Calcium (Ca2+)

Strontium (Sr 2+)

Potassium (K +)

Barium (Ba 2+)

Copper (Cu 2+)

Lithium (Li 1+)

Unknown Questions – Weave these in! 1. Describe what happens to the electrons in an element when the element is heated to high temperatures.

2. If we use a different solution with the same metal ion will the flame test results change? Why or why not?

3. Explain why the metal ions emit light of different colors when heated.

4. What are the pros and cons of using the flame tests to identify metal ions in solution?

5. List the flame colors you observed in order from highest wave energy to lowest wave energy.