1. 4.8 – NOTES Intro to Electron Configurations

2. II. Quantum Theory and the Atom
A. Bohr model of the atom – 1913
1. Energy states of hydrogen (only certain allowable energy states)
Ground state: lowest allowable energy state, Bohr proposed e- resides in an orbit, the smaller the orbit, the lower the energy; assigned a number (n) to each orbit and calculated the radius of each orbit
Excited State: occurs when an electron gains energy; will quickly release energy, usually in the form of light

4. 2. An explanation of hydrogen’s line spectrum - expected discontinuous, suggested in ground state with an n = 1, when energy added electron moves to excited state (n=2), moves to ground state and emits energy/photon;
- shows H actually moves to N = 3, 4, or 5 energy level and drops to 2nd; gives us spectrum; could only describe H;

5. Hydrogen – 1 electron, multiple levels of excitement!!!!!

6. B. The quantum mechanical model of the atom
1. Electrons as waves Bohr’s quantized orbits similar to waves;
The de Broglie relation – 1924
λ = h/mν; all moving particles have wave-like characteristics; only visible in small particles like electrons

7. C. The Heisenberg Uncertainty Principle
1. It is impossible to make a measurement on an object without disturbing the object in some way, especially if the object is very small.
- Heisenberg’s Uncertainty Principle states that impossible to know the speed and location of an electron at the same time

8. 2. The Schrödinger wave equation – 1926 does nothing to describe the electron path around the nucleus,
- predicts a region around the nucleus where the electron might be located;
3. Atomic orbitals
3 – dimensional region around the nucleus where electrons can be found. An orbital has no definite outer boundary. An orbital is also called a probability function.

10. D. Hydrogen’s atomic orbitals
1. The position of an electron is described by 4 quantum numbers:
Principal quantum number, n
- energy level of the electron (for H); relates the average distance of the electron from the nucleus in an orbital
Sublevel quantum number, ℓ
- Angular Momentum Quantum Number; gives us shape; aka called orbital quantum #
Magnetic quantum number, mℓ
- orientation in space
Spin quantum number, ms

13. 2. The 7 energy levels Energy Level Shell # of Sublevels
# of Sublevels
Sublevels Present
Sublevel Names
# of orbitals
(n2)
# of e-
(2n2) 1 K s 1s 2 L
s,p
2s, 2p 4 8 3 M
s, p, d
3s, 3p, 3d 9 18 N
s, p, d, f
4s, 4p, 4d, 4f 16 32 5 O
s, p, d, f, g
5s, 5p, 5d, 5f, 5g 25 50 6 P
s, p, d, f, g, h
6s, 6p, 6d, 6f, 6g, 6h 36 72 7 Q
s, p, d, f, g, h, i
7s, 7p, 7d, 7f, 7g, 7h, 7i 49 98
2. The 7 energy levels

14. s = sharp (defined)
d = diffuse (spread out)
p = principle (very strong)
f = fundamental