1. Electrons in Atoms Bohr Model
Chapter 3
Electrons in Atoms
Bohr Model

2. Bohr’s Model
Nucleus
Electron
Orbit
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Energy Levels

3. Student check for understanding Bohr’s Model
Evaluate the Bohr model on its positive merits and its negative merits

4. Student check Bohr’s Model
Why don’t the electrons fall into the nucleus?

5. Student check Bohr’s Model
Why don’t the electrons fall into the nucleus?
Forces: Gravitational
Centrifugal outward force
Centripetal force

6. } Bohr’s Model Further away from the nucleus means more energy. Fifth
There is no “in between” energy
Energy Levels
Fifth
Fourth
Third
Increasing energy
Second
Hyper link
First
Nucleus

7. The Quantum Mechanical Model
Energy is quantized. It comes in chunks.
A quanta is the amount of energy needed to move from one energy level to another.
Since the energy of an atom is never “in between” there must be a quantum leap in energy.

8. Atomic Orbitals
Principal Quantum Number (n) = the energy level of the electron.
These are called atomic orbitals
Regions where there is a high probability of finding an electron.

9. Light
The study of light led to the development of the quantum mechanical model.
Light is a kind of electromagnetic radiation.
Electromagnetic radiation includes many kinds of waves
All move at 3.00 x 108 m/s ( c)

10. Parts of a wave
Crest
Wavelength
Amplitude
Origin
Trough

11. Frequency
The number of waves that pass a given point per second.
Units are cycles/sec or hertz (hz)
Abbreviated n the Greek letter nu
c = ln

12. Frequency and wavelength
Are inversely related
As one goes up the other goes down.
Different frequencies of light is different colors of light.
There is a wide variety of frequencies
The whole range is called a spectrum

13. Low energy High energy Radiowaves Microwaves Infrared . Ultra-violet
X-Rays
GammaRays
Low Frequency
High Frequency
Long Wavelength
Short Wavelength
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Visible Light

14. Student Check Inversely related?
If radio waves have a low frequency what happens to their wavelength?
If gamma rays have a short wavelength what happens to their frequency

15. How color tells us about atoms
Atomic Spectrum
How color tells us about atoms

16. Prism
White light is made up of all the colors of the visible spectrum.
Passing it through a prism separates it.
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17. If the light is not white
By heating a gas with electricity we can get it to give off colors.
Passing this light through a prism does something different.

18. Atomic Spectrum Each element gives off its own characteristic colors.
Can be used to identify the atom.
How we know what stars are made of.

19. These are called discontinuous spectra
Or line spectra
unique to each element.
These are emission spectra
The light is emitted given off.
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20. Spectrum and the stars
How can you use the spectrum to determine what the sun is made of.
What other information can be determined look at the emission spectrum
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Temp/speed/ age

21. Light is a Particle Energy is quantized. Light is energy
Light must be quantized
These smallest pieces of light are called photons.
Energy and frequency are directly related.

22. After Before Photon changes wavelength Photon
Electron Changes velocity
Moving Electron

23. Student check
Summarize how Light is produced using the Bohr model

24. Flame test
Flame test
Radium girls
Duck song