Lab 11: Flame Test Lab
Summary/Introduction:
When atoms are heated to high temperatures, some electrons may absorb energy and jump from ground state, the most stable energy state, to higher energy levels, where the element is then said to be in an excited state. As the electrons "fall back" to their ground state after being in an excited state, the energy that was absorbed is released as electromagnetic radiation, some of which is in the form of visible light. In this lab, the flame colors exhibited from different metallic ions are the emitted photons of visible light that were vaporized by burner. Furthermore, different metallic ions release waves of different wavelengths, which correspond to contrasting colors. Thus, by observing the color of a flame, the unknown ions can often be identified.
Pre Lab Questions:
What is the difference between ground state and an excited state?
Ground state is where electrons of an atom are in their normal configurations and are in their most stable energy state, as long as the lowest energy levels available. In contrast, excited state is where the electrons are in an unstable configuration and then fall back to lower energy levels and release electromagnetic radiation.
What does the word "emit" mean?
Essentially, emit means the same as release. So when waves/photons were emitted in the lab, they were released.
In this experiment, where are the atoms getting their excess energy from?
Atoms are getting their excess energy from the heat of the flame. As aforementioned, when atoms or ions in ground state are heated to high temperatures, some electrons may absorb energy and jump to higher energy levels.
Why do different atoms emit different colors of light?
Different atoms emit different colors of light because they have different spacings in their energy levels. Atoms that have electrons that do not "jump" as far will emit waves of dissimilar wavelengths because they absorb different amounts of energy, which correspond to separate colors.
Analysis Questions:
What patterns do you notice in the groupings?
There were two groupings that we noticed patterns in. First, we observed that substances that emitted an orange color either had Na(+) or Ca(2+) metallic ions. Second, we observed that all substances with copper emitted a blue/green flame color.
What evidence do you have that atoms of certain elements produce a flame of a specific color?
We saw that all three substances which had the Copper metallic ion exhibited a blue/green flame when vaporized. Additionally, both substances with the Sodium ion exhibited an orange flame color.
Can a flame test be used to identify a metal atom in a compound? Why or why not? What about a nonmetal atom?
A flame test can be used to identify a metal atom in a compound because metallic ions have loosely spaced electrons, thus emitting waves that are a part of the visible electromagnetic spectrum . Nonmetal ions don't emit waves that are part of the visible spectrum, so we can't identify them based on the color of the flame emitted.
Identify the two unknowns. What are they and how do you know?
Unknown #1 had a bright pink colored flame; the only other compound that emitted such a color was LiCl, so Unknown #1 must have been Lithium Chloride. Unknown #2 had a purple/lilac hue flame; the only other compound that emitted such a hue was Potassium Chloride.
Copper oxide, CuO, is a black solid. It doesn't look at all like the element copper. What color flame would it produce.
Copper oxide, like all the other compounds with Copper in this lab, will emit a green/blue flame.
Favorite Flame Test:
My favorite flame test was the copper chloride compound because its vibrant color reminded me of the northern lights.
When atoms are heated to high temperatures, some electrons may absorb energy and jump from ground state, the most stable energy state, to higher energy levels, where the element is then said to be in an excited state. As the electrons "fall back" to their ground state after being in an excited state, the energy that was absorbed is released as electromagnetic radiation, some of which is in the form of visible light. In this lab, the flame colors exhibited from different metallic ions are the emitted photons of visible light that were vaporized by burner. Furthermore, different metallic ions release waves of different wavelengths, which correspond to contrasting colors. Thus, by observing the color of a flame, the unknown ions can often be identified.
Pre Lab Questions:
What is the difference between ground state and an excited state?
Ground state is where electrons of an atom are in their normal configurations and are in their most stable energy state, as long as the lowest energy levels available. In contrast, excited state is where the electrons are in an unstable configuration and then fall back to lower energy levels and release electromagnetic radiation.
What does the word "emit" mean?
Essentially, emit means the same as release. So when waves/photons were emitted in the lab, they were released.
In this experiment, where are the atoms getting their excess energy from?
Atoms are getting their excess energy from the heat of the flame. As aforementioned, when atoms or ions in ground state are heated to high temperatures, some electrons may absorb energy and jump to higher energy levels.
Why do different atoms emit different colors of light?
Different atoms emit different colors of light because they have different spacings in their energy levels. Atoms that have electrons that do not "jump" as far will emit waves of dissimilar wavelengths because they absorb different amounts of energy, which correspond to separate colors.
Analysis Questions:
What patterns do you notice in the groupings?
There were two groupings that we noticed patterns in. First, we observed that substances that emitted an orange color either had Na(+) or Ca(2+) metallic ions. Second, we observed that all substances with copper emitted a blue/green flame color.
What evidence do you have that atoms of certain elements produce a flame of a specific color?
We saw that all three substances which had the Copper metallic ion exhibited a blue/green flame when vaporized. Additionally, both substances with the Sodium ion exhibited an orange flame color.
Can a flame test be used to identify a metal atom in a compound? Why or why not? What about a nonmetal atom?
A flame test can be used to identify a metal atom in a compound because metallic ions have loosely spaced electrons, thus emitting waves that are a part of the visible electromagnetic spectrum . Nonmetal ions don't emit waves that are part of the visible spectrum, so we can't identify them based on the color of the flame emitted.
Identify the two unknowns. What are they and how do you know?
Unknown #1 had a bright pink colored flame; the only other compound that emitted such a color was LiCl, so Unknown #1 must have been Lithium Chloride. Unknown #2 had a purple/lilac hue flame; the only other compound that emitted such a hue was Potassium Chloride.
Copper oxide, CuO, is a black solid. It doesn't look at all like the element copper. What color flame would it produce.
Copper oxide, like all the other compounds with Copper in this lab, will emit a green/blue flame.
Favorite Flame Test:
My favorite flame test was the copper chloride compound because its vibrant color reminded me of the northern lights.
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