Chemistry Flame Test Lab

h is

Planck's constant

Summarize the process that produces the colors seen in the flame tests.

The atom starts in the ground state. We add energy to the atom with the bunsen burner. Atom absorbs this energy and electrons jump to higher (discrete) energy levels. Electrons quickly return to the ground state, emitting a discrete amount of energy as a photon of light. We see the colors produced.

When a glass rod is heated, a yellow flame is observed around the point of heating. What does this yellow flame indicate? Why is it observed when glass is heated?

The bright yellow flame indicates there are sodium compounds used in the making of glass

What does a flame test indicate about the energy changes taking place among the electrons in a metallic ion?

The colors indicate the specific energy changes occurring in the ion

What is the relationship of the colors you saw and the lines of the electromagnetic spectrum produced by the metals.

The colors we saw were a combination of the lines of the visible spectrum produced by the metals.

How do you think metallic salts are used in fireworks?

The salts are heated (producing excited state atoms). When the atoms return to the ground state, the produce colors.

What wavelengths correspond to the visible spectrum? Which color has the shortest wavelength?

4x10-7m to 7x10-7m shortest- violet longest- red

The line spectrum of lithium has a red line at 670.8 nm. Calculate the energy of a photon with this wavelength.

E=hc/lamda h=6.626x10-34 JS C=3.00x10^8 m/s 670,8 nm = 6.708x10-7m E= (h)(c)/6.708x10-7 E= 3.00x10-19 J

The energy of each photon is described by the equation

E=hv

Explain how cross-contamination would ruin the results of the experiment?

Each ion produces its own color due to the energy level changes in that ion. Cross-contamination would give us a mixture of colors.

What other equipment could you use in this investigation if burners were not available?

Electric current- produce a spark- salts are saturated with alcohol

Were all the salts listed in the data table used in the experiment? Give an example of one that was different? Would using the different salt have an effect on the experiment?

No. We used calcium chloride in replace of calcium nitrate. This has no effect on the experiment since we are looking at energy level changes in the calcium.

Explain why a metallic ion produces a characteristic color in a flame test, regardless of the compound used as the source of the ion

We are witnessing the energy changes in the ion. Doesn't matter what compound it is. The loosely held electrons of a metal are easily excited.

_______ is a continuous spectrum in which all wavelengths of visible light are present

White light

What were the cations used?

barium copper lithium potassium sodium calcium strontium

The emission of energy in the visible portion of the spectrum as those electrons return to lower energy levels produces a

colored flame

If a lower energy level is available, the electron will fall back, giving off

energy in the process

The loosely-held electrons of a metal are easily excited in the

flame of a lab burner

_______ are a quick method of producing the characteristic colors of metallic ions

flame tests

v is

frequency

How do you hold the burner?

horizontally

The color is a combination of the wavelengths of each transition, and may be used to determine the

identity of the ion

When an atom absorbs sufficient energy, and electron can

jump to a higher energy level

Higher energy levels tend to be _____

less stable

Because each element has a distinct electron configuration, each has a unique

line spectrum

According to the Bohr theory of the atom, electrons

may occupy only specific energy levels

The color of the light depends

on the specific energy change that is taking place

The difference in energies between the two levels is emitted in the from og a

photon of electromagnetic radiation

An excited atom, however, produces one or more specific lines in its spectrum, corresponding to the

specific changes in energy levels of its electrons

If the wavelength of the released photon is between 400 and 700 nm, the energy is emitted as

visible light