1. Quantum Mechanical Model & Orbitals

2. Development of Atomic Models
These illustrations show how the atomic model has changed as scientists learned more about the atom’s structure.

3. Where are the electrons exactly?
propeller has equal probability of being anywhere in the blurry region, but…
…you cannot tell its exact location at any instant.
(NOT THE BEST ANALOGY, BUT GOOD ENOUGH)
The electron cloud of an atom is compared here to photographs of a spinning airplane propeller. a) The airplane propeller is somewhere in the blurry region it produces in this picture, but the picture does not tell you its exact position at any instant. b) Similarly, the electron cloud of an atom represents the locations where an electron is likely to be found.

4. Quantum Mechanical Model (Electron Cloud)
(1926–Erwin Schrodinger & others)
shows most probable locations of electrons
equations describe electrons as waves in motion through space

5. Quantum Mechanical Model
The electron is visualized not as a particle at some location in the atom, but its mass and charge are spread as a standing wave around the nucleus.
energy levels 1,2,3,4 straightened out

6. Quantum Mechanical Model
Bohr’s model shows electrons orbit the nucleus like planets going around the sun.
de Broglie’s idea shows a wave along an orbit.
Quantum Mechanical model:
electrons are in a 3D “cloud” of orbits of wave equations (math) and probability.

7. energy levels have sublevels of different shapes (not perfect rings)
5.2
Atomic Orbitals
Atomic Orbitals
energy levels have sublevels of different shapes (not perfect rings like Bohr proposed)

8. energy levels have sublevels of different shapes (not perfect rings)
5.2
Atomic Orbitals
Atomic Orbitals
energy levels have sublevels of different shapes (not perfect rings like Bohr proposed)

9. 2s 2p 1s 3s Electron energy levels have sublevels of different shapes
orbital
Nucleus 2p
orbitals 1s
orbital 3s
orbital

10. 3-D regions with a high probability of electrons atomic orbitals:
s orbitals are
spherical
p orbitals are dumbbell-shaped in 3 directions
d orbitals are clover-shaped in… there are 5 of them.
*** DRAW
ALL OF
s p and d
maybe even f
f-orbitals
are funky-shaped
there are 7 of them.

11. Development of Atomic Models
1803 Dalton
1904 Thomson
1911 Rutherford
1913 Bohr
These illustrations show how the atomic model has changed as scientists learned more about the atom’s structure.
1926 Quantum Mechanical Model

12. Quick Quiz!
1. What does the quantum mechanical model describe about atoms?
the probable locations of electrons in atoms
the precise locations of electrons in atoms
the number of electrons in an atom
how crazy chemistry is

13. Quick Quiz.
2. What do orbitals (s, p, d, f) tell us about the sublevel of an electron?
the amount of energy in each electron
the number of electrons in each sublevel
the shape of the region they occupy
that my brain feels mushy now