1. Unit 3 – Electron Configurations Part B: Bohr’s Model of Hydrogen
Dr. Chin Chu
River Dell Regional High School

2. What have we learned so far?
Discharging Tubes
The Flame Test
The light coming out of the excited atomic entities is very specific to particular element!
Results are quite reproducible.

3. Conclusions:
Electromagnetic radiations (lights) coming out or being absorbed by atoms indicate that there are very specific energy changes within the atomic entities (atoms and ions).
No nuclear changes have ever been observed indicate that the energy changes have to come from electrons surrounding the nucleus.

4. How come?
Classic Model:
Problems with the classic model:

5. Niels Bohr (1885 – 1962)

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

7. Bohr’s Model of Hydrogen Atom
quantum – quantity of energy gained or lost by an atom when electrons are excited
photon – a quantum of light
ground state – lowest energy level of an atom
excited state – a heightened state of energy in an atom
Electrons of hydrogen circle the nucleus in orbits
1. orbits have a fixed amount of energy in the ground state.
2. orbits are a fixed distance from the nucleus.
3. orbits furthest from the nucleus have the greatest energy.

8. Bohr’s Model of Hydrogen Atom

9. Bohr’s Model of Hydrogen Atom

10. Bohr’s Model of Hydrogen Atom

11. Bohr’s Model of Hydrogen Atom

12. Bohr’s Model of Hydrogen Atom