1. Topic: Atomic Concepts Aim: What is the difference between ground state and excited state electron configurations? How can we identify unknown elements?
HW:

2. Ground State vs. Excited State
States in which e- can exist
Ground State: lowest energy e- config.
Shown on Periodic Table
Innermost PEL fills first, then work outward

3. Ground State vs. Excited State
Excited State: e- can move to a higher PEL without filling the lower energy level first
Do this by absorbing energy
Excited e- fall back to ground state by releasing energy
Energy released called quanta

4. Diagram
Elements give off different colors depending on the amount of energy released
(how far the e- falls)

5. Neon – Ground vs. Excited State

6. Examples Fluorine Ground state e- config (Periodic Table)
2-7
Possible excited state e- configs
1-7-1
2-6-1
1-8
Note how an inner level is left partially filled b/c an e- has jumped to a higher PEL
Note that TOTAL # OF e- REMAINS THE SAME!

7. Sample Questions
1. Which is the electron configuration of an atom in the excited state?
A) 2 – 8 – 2 C) 2 – 7 - 1
B) 2 – 8 – 1 D) 2 – 8 – 3
2. Which electron configuration represents an atom in the excited state?
A) 1 – 2 C)
B) 2 – 1 D)

8. Bright Line Spectrum
Formed from e- falling from excited state to ground state
Each element has its own bright-line spectrum
Therefore, this is 1 way to ID specific elements

9. Ex. The bright-line spectrum of lithium looks like this:
So, if you have unknown samples & you want to know if 1 of them is lithium, compare the unknown elements’ spectra with the known spectrum for lithium.

10. More Bright-Line Spectra

11. Flame Test Another way to ID elements Element heated
e- move to excited state (due to absorbing energy)
e- fall back to ground state (due to releasing energy)
Flame turns color specific to that element

13. Flame Test Colors

14. Sample Questions
1/03 During a flame test, ions of a specific metal are heated in the flame of a gas burner. A characteristic color of light is emitted by these ions in the flame when the electrons
gain energy as they return to lower energy levels
emit energy as they return to lower energy levels
gain energy as they move to higher energy levels
emit energy as they move to higher energy levels
Which electron configuration represents the excited state of a calcium atom?
What is the element Z?