Question

background: the normal electron configuration of atoms or ions of an element is known as the \ground state.\ in this most stable energy state, all electrons are in the lowest energy levels available. when atoms or ions in the \ground state\ are heated to high temperatures, some electrons may absorb enough energy to allow them to \jump\ to higher energy levels. the element is then said to be in the \excited state.\ this excited configuration is unstable, and the electrons \fall\ back to their normal positions of lower energy (ground state). as the electrons return to their normal levels, the energy that was absorbed is emitted in the form of electromagnetic energy. some of this energy may be in the form of visible light. the color of this light can be used as a means of identifying the elements involved. such analysis is known as a flame test.
to do a flame test on a metallic element, the metal is first dissolved in a solution and the solution is then held in the hot, blue flame of a bunsen burner. this test works well for metal ions, and was perfected by robert bunsen (1811 - 1899). many metallic ions exhibit characteristic colors when vaporized in the burner flame. the colors of the flame are produced because of the electrons changing energy levels and emitting varying amounts of energy in the form of light, which we see as different colors.
purpose: the purpose is to observe the characteristic colors produced by certain metallic ions when vaporized in a flame and then to identify an unknown metallic ion by means of its flame test.
materials: set of metal chloride solutions (nacl, cucl₂, kcl, cacl₂, srcl₂, licl, nacl, bacl₂) bunsen burner 8 - 10 q - tips or 10 soaked wooden splints unknown solution (for each student)
safety: what safety must you follow? (hint: you are dealing with fire, chemicals, gas)
define the following as they relate to electrons.
ground state:
excited state:
pre lab questions:

1. the first element listed in the compounds shown in the data table are metals. write down the atomic number, period number (row #), and group number (column #) for each \metal\ and place in each of the designated columns.
2. how does an electron move from its ground state to an excited state? when will you see a color?

Explanation:

1. Safety: Wear safety goggles to protect eyes from chemical splashes and fire - related debris. Work in a well - ventilated area to avoid inhaling chemical fumes. Keep flammable materials away from the Bunsen burner. Use tongs or heat - resistant gloves when handling hot objects. Follow proper chemical handling procedures for storing and disposing of the metal chloride solutions.
2. Ground State: The ground state of an electron is the most stable energy state of an electron in an atom or ion, where all electrons are in the lowest available energy levels.
3. Excited State: An excited state of an electron occurs when an atom or ion in the ground state is heated or receives energy, causing some electrons to absorb enough energy to "jump" to higher energy levels. This state is unstable.
4. Pre - Lab Question 1:

• For Na in NaCl: Atomic number is 11, period number is 3, group number is 1.
• For Cu in CuCl₂: Atomic number is 29, period number is 4, group number is 11.
• For K in KCl: Atomic number is 19, period number is 4, group number is 1.
• For Ca in CaCl₂: Atomic number is 20, period number is 4, group number is 2.
• For Sr in SrCl₂: Atomic number is 38, period number is 5, group number is 2.
• For Li in LiCl: Atomic number is 3, period number is 2, group number is 1.
• For Ba in BaCl₂: Atomic number is 56, period number is 6, group number is 2.

1. Pre - Lab Question 2: An electron moves from its ground state to an excited state when it absorbs energy, such as heat energy in the case of a flame test. You will see a color when the excited electrons "fall" back to their ground state and emit energy in the form of electromagnetic radiation, some of which may be in the visible light spectrum.

Answer:

1. Safety: Wear safety goggles, work in a well - ventilated area, keep flammable materials away, use tongs/gloves for hot objects, follow chemical handling procedures.
2. Ground State: The most stable energy state with electrons in lowest levels.
3. Excited State: State when electrons jump to higher levels due to energy absorption, unstable.
4. Pre - Lab Question 1:

• Na: Atomic number 11, period 3, group 1.
• Cu: Atomic number 29, period 4, group 11.
• K: Atomic number 19, period 4, group 1.
• Ca: Atomic number 20, period 4, group 2.
• Sr: Atomic number 38, period 5, group 2.
• Li: Atomic number 3, period 2, group 1.
• Ba: Atomic number 56, period 6, group 2.

1. Pre - Lab Question 2: Electron absorbs energy to move to excited state. Color is seen when electrons return to ground state and emit visible light.