Flame Test Lab.pdf

Flame test lab Eli Brandt Introduction This lab is to investigate the energy released when certain elements are held above a flame, as observed by different color of flames. The Normal electron configuration for ions and atoms of an element is the ground state. When the elements are heated to high temperatures the electrons will leap to higher energy levels because of the increased energy. This is when the element is in an exited state. The elements do not stay this way as they are unstable so the electrons fall back down to lower levels, causing the extra energy to be released in the form of different colored flames. The objectives of this lab were to use data gained by using the Spectrometer in order do to compare the data different elements and the energy they released. My hypothesis states that the more stable the element the lower the wavelength. I made this guess because the energy that pushes the electrons back down to their original level is the electrons pushing each-other away, and the more stable an atom the more valance electrons on the outer shell pushing the exited electrons back into their original place. So it takes less energy for this process to happen for atoms with more valance electrons. Methods: Describing the lab procedure Turn the spectrometer on by holding the power button, then check ID number on bottom of spectrometer and connect to iPad through Bluetooth. After you do that connect the fiber optic cable into the the spectrometer, and open SpectrometerApp. Click the analyze light function and change the exposure to 1000 ms. For the elements that you are burning wet a popsicle stick under the tap and dip it into the element so that there is a coating on the stick before you put it over the Bunsen burner. During the demonstration, record the color of each flame. Make sure to hold the fiber optic attachment 2-3 inches from the flame, taking care to not burn your hand and the equipment. When recording, make note of which graph corresponds with which element or tube so you don’t get the results mixed up. For the special tubes just hold the spectrometer up to the tube, and turn on the device. Make sure you photograph all the results, and record them in a way similar to figure one.

Data and results figure 1

Element tested

Atomi c#

Lithium

3

Copper

Number of Color of valance flame electrons

Picture of flame

Picture of graph

Highest wavelength

1 Red

660.779 nm

29

2 Blue/ turquoise

534.160 nm

Calcium

20

2 Orange

609.300 nm

Sodium

11

1 Light orange

579.878 nm

Barium

56

2 Orange

580.702 nm

Strontium

38

2 Red

659.693 nm

Potassium

19

1 Dull purple

757.475 nm

Argon

18

8 Purple

802.304 nm

Krypton

36

8 Light purple

748.616 nm

Figure 2

Element tested

Atomi c#

Number of Color of valance flame electrons

Hydrogen

1

1 Pink/ white/ blue

Helium

2

8 Orange white

Picture of flame

Picture of graph

Highest wavelength 646.616 nm

577.684

The main thing I found in this lab is that the wavelength is higher for less stable elements, but excluding noble gasses.

Discussion: Interpreting the results of the lab This data partially supports my hypothesis because the less stable elements released more energy then those with more valence electrons, but for a unknown reason the noble gasses did not follow this pattern. The reason my hypothesis is correct is if you look at figure 2, the scatter plot of the wave lengths, the wavelengths were generally higher for elements that had one valence electron, compared to having two. The average wavelength of elements with 1 valence electron was 661.187 nm while the average with two valence electrons was 595.963 nm which is marginally lower. The data that causes my hypothesis to be partially true is the noble gasses which had a higher average wavelength then they should have had. The scientific concept of the lab is an electron gaining energy and jumping to a higher energy level. When the electron goes back to a lower shell to become grounded again it releases energy. My hypothesis stated that because stable elements have more valence electrons there would be less space for the electron to fill and it would require less energy for the elements to be pushed back down due to the electrons pushing the exited electron down. My hypothesis was partially true, and I realize now that perhaps the reason that my theory was disproved for noble gasses is that since the noble gasses have a full outer shell, the electron that was exited jumped all the way up to create a new energy level in which it is the only valence electron, and since no other electrons were pushing it down that electron released a higher amount of energy when it fell back to its original position which is why the noble gasses had such high wavelengths. One uncertainty in this lab was the flash from the iPads camera when taking photos. I noticed that the photos were better with flash so is switched. But I don’t know if or how this affected the spectrometer readings because it was recording at the same time as when the photos were taken because the flame only lasted so long before we started burning the wood of the popsicle stick. The flash could have messed up the results, but other classmates did not use flash and had similar results in this lab so there probably wasn’t a problem, but it probably was not a good idea to use flash photography none the less. In terms of improving this lab, I thought it would be a good idea to understand the concept of the lab more before we started in order to create a hypothesis before, not after the lab was completed.