1. Bohr vs the quantum mechanical model of the atom
6.2 and 6.3
Bohr vs the quantum mechanical model of the atom

2. 6.2 and 6.3: Bohr and the quantum mechanical model
Compare the Bohr and quantum mechanical models of the atom.
Explain the impact of de Broglie's wave article duality and the Heisenberg uncertainty principle on the current view of electrons in atoms.
Identify the relationships among a hydrogen atom's energy levels, sublevels, and atomic orbitals.
atom: the smallest particle of an element that retains all the properties of that element, is composed of electrons, protons, and neutrons.

3. Section 5.2 Quantum Theory and the Atom (cont.)
ground state
quantum number
de Broglie equation
Heisenberg uncertainty principle
quantum mechanical model of the atom
atomic orbital
principal quantum number
principal energy level
energy sublevel
Wavelike properties of electrons help relate atomic emission spectra, energy states of atoms, and atomic orbitals.

4. Review: Electrons (ground state and excited state)

5. So why did we get lines in the spectroscope?
Niels Bohr (1885 – 1962)
Worked with Rutherford
Model of the hydrogen atom: the single electron of the hydrogen atom can circle the nucleus only in allowed paths called orbits
Lowest energy = closest orbit to the nucleus

6. Bohr model of the atom

7. Bohr's Model of the Atom (cont.)
Bohr suggested that an electron moves around the nucleus only in certain allowed circular orbits.

8. Bohr's Model of Hydrogen

9. Bohr's Model of the Atom (cont.)
Each orbit was given a number, called the quantum number.

10. Importance of Bohr Model
Using charge and mass of an electron and Planck’s constant (E=hν)
Calculated the energies that an electron should have in the orbits.
This can then compare to the line spectrum seen, and the calculations were correct
Energy Bohr model said electron should have, was the same energy that the colored lines produced from the bright line spectrum

11. Problem with Bohr Model
His mathematics only applied to the Hydrogen atom

12. Bohr Model of the Atom Bohr: Orbit: electrons were treated as:
correctly predicted line spectrum for __________, but could not for any other element

13. What to do now ?? Bohr treated electrons like particles
1924: Louis de Broglie noticed that the spectrum lines could be explained by wave properties
Example: waves confined in a space have only certain frequencies.

14. The Quantum Mechanical Model of the Atom (
The figure illustrates that electrons orbit the nucleus only in whole-number wavelengths.

15. The Quantum Mechanical Model of the Atom (cont.)
The de Broglie equation predicts that all moving particles have wave characteristics.
 represents wavelengths h is Planck's constant. m represents mass of the particle.  represents frequency.

16. Heisenberg Uncertainty Principle
The Heisenberg uncertainty principle states that it is fundamentally impossible to know precisely both the velocity and position of an electron at the same time.
The only quantity that can be known is the probability for an electron to occupy a certain region around the nucleus.

17. Heisenberg Uncertainty Principle
To see something, light must hit the object, bounce off it, and come back to our eye
When light hits an electron, it makes it move because the electron is so small.
By the time the reflected light gets back to our eye, the electron is no longer where it was.

18. The Quantum Mechanical Model of the Atom
Using de Broglie’s and Heisenburg’s thoughts
Schrödinger treated electrons as waves in a model called the quantum mechanical model of the atom.
Schrödinger’s equation applied equally well to elements other than hydrogen.

19. Erwin Schrödinger, 1926 Who has worked with the sin and cosine curve?
Basically, he applied a wave formula (like sin or cosine) to the properties of the electrons
Worked for all atoms
Create electron orbitals instead of orbits
Can not pinpoint the location of the electron

21. The Quantum Mechanical Model of the Atom
The wave function predicts a three-dimensional region around the nucleus called the atomic orbital.

22. Orbitals
Three dimensional region about the nucleus in which a particular electron can be located

23. Hydrogen Atomic Orbitals (cont.)
Each energy sublevel relates to orbitals of different shape.

24. Schrodinger
Orbitals - Mathematical representations of where electrons could be (Not specific)
Can not ………._______________
Treated electrons as _________

25. Result of Schrodinger Quantum Theory
Mathematically describes the wave properties of electrons
Creates orbitals which when added together, look like an electron cloud