1. Electrons and Energy Levels

2. What we know about electrons so far…..
What charge are electrons?
Do electrons account for the mass of an atom?
Where are electrons located?

3. ELECTRONS! Neils Bohr proposed the concept of energy levels.
Bohr model of the atom:
Neils Bohr proposed the concept of energy levels.
Energy Level Rules:
electrons fill the lowest energy level first (lazy)
each energy level can only hold a certain amount of electrons
there are only whole number energy levels (i.e. can’t have energy level 2.5)

4. Check-in:
Each circle represents 1 electron, color in the circles where the electrons will go for an atom of sodium for each diagram below.

5. Energy Levels

6. Current Model of the Atom
In the current model of the atom, we think of the electrons as moving around the nucleus in an area called an electron cloud.
The energy levels occur because electrons in the cloud are at different average distances from the nucleus.

7. Spectra Tubes What do you notice about the different tubes?
Do all the tubes look the same?
Why do you think they look different?

8. Why do the compounds emit a color?!
When electrons are heated they get “excited!”
What do you mean excited?!
Electrons exist in atoms in specific levels (energy levels)
Electrons are lazy (just like 9th graders) and stay in the lowest energy state until they are “forced” out

9. Why do the compounds emit a color?!
How are electrons “forced” out from a level?
With energy!
In our case electricity

10. Why do compounds emit a color?!
Even Higher Energy Level
Higher energy level
When heat is added
to the compound….
An electron in the compound
moves up to a higher energy
level.
Ground State
(lowest energy state) e

11. Why do compounds emit a color?!
Even Higher Energy Level
Electrons only stay in
the higher energy level
for a short period of time. e
Higher energy level
THEN they move back
down to the lowest
energy level.
Ground State
(lowest energy state)

12. Why do compounds emit a color?!
Even Higher Energy Level
As they move down to
a lower energy level…..
Higher energy level
LIGHT!
(color)
Energy is released (remember
we must conserve energy) in the
form of LIGHT!!!
Ground State
(lowest energy state) e

13. Why do compounds emit a color?!
Even Higher Energy Level
We call this LIGHT
energy that is being
released by an electron
a PHOTON!!
Higher energy level
LIGHT!
(color)
Ground State
(lowest energy state) e

14. Electron Moving from Ground State to Excited State…

15. Electron Moving from Excited State Back to Ground State….

16. Atomic Spectrums
Each different element has its own characteristic pattern of colors called a spectrum.
The colors of clothes, paint, and everything else around you come from this property of elements to emit or absorb light of only certain colors.