Development of Atomic Models

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.

• shows most probable locations of electrons

•equations describe electrons as waves in motion through space

Quantum Mechanical Model (Electron Cloud)(1926–Erwin Schrodinger & others)

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

Quantum Mechanical Model

a. Bohr’s model shows electrons orbit the nucleus like planets going around the sun.

b. de Broglie’s idea shows a wave along an orbit.

c. Quantum Mechanical model:electrons are in a 3D “cloud” of orbits of wave equations (math) and probability.

Quantum Mechanical Model

Atomic Orbitals5.2

Atomic Orbitals

energy levels have sublevels of different shapes (not perfect rings like Bohr proposed)

energy levels have sublevels of different shapes (not perfect rings)

Atomic Orbitals5.2

Atomic Orbitals

energy levels have sublevels of different shapes (not perfect rings like Bohr proposed)

energy levels have sublevels of different shapes (not perfect rings)

atomic orbitals:

s orbitals are

spherical

p orbitals are dumbbell-shaped in 3 directions

3-D regions with a high probability of electrons

d

f

1sorbital

2sorbital

2porbitals

3sorbital

Nucleus

Electron energy levels have sublevels of different shapes

1803 Dalton

1904 Thomson

1911 Rutherford

1913 Bohr

1926 Quantum Mechanical Model

Development of Atomic Models

1. What does the quantum mechanical model describe about atoms?

A. the probable locations of electrons in atoms

B. the precise locations of electrons in atoms

C. the number of electrons in an atom

D. how crazy chemistry is

Quick Quiz!

2. What do orbitals (s, p, d, f) tell us about the sublevel of an electron?

A. the amount of energy in each electron

B. the number of electrons in each sublevel

C. the shape of the region they occupy

D. that my brain feels mushy now

Quick Quiz.