Hydrogen’s Atomic Orbitals

The Heisenberg Uncertainty PrincipleIn the late 1920’s, Werner Heisenberg, concluded that is

impossible to make any measurement of an object without disturbing that object.

Photons have the same energy as electrons, so they would change the electron’s wavelength

and velocity

Electron Density Diagram

In 1926, Erwin Schrodinger developed a probability model for the electron’s position.

The electron density model represents the probability of

finding the electron at a particular point in the atom. 90% Probability

Quantum Mechanical ModelThe quantum mechanical model of the atom still limits

an electron’s energy to certain values (Bohr’s)

However, the model makes no attempt to

describe the electron’s path around the nucleus.

(wave)

Atomic OrbitalsCurrent theory of atoms have the electrons orbiting the nucleus, in wave-like patterns, within three dimensional

regions of high probability called atomic orbitals.

Principal Quantum NumbersEven though the electrons do not stay in circular orbits

around the nucleus, they do still stay in regions with different energy levels.

Principal quantum numbers (n) are used

to indicate the relative size and energies of

atomic orbitals.

Principal Energy Levels

As n increases, the orbital becomes larger, the electron

spends more time away from the nucleus, and the atom’s energy

level increases.

Atoms can have up to 7 principal energy levels

Energy SublevelsWithin each principal energy level, the electrons tend to

stay in specific regions, called sublevels.

The number of sublevels within each principal

level increases with the quantum numbers of the

principal levels.

Atomic Sublevel OrbitalsAtomic sublevel orbitals are labeled s, p, d, and f

according to the shape of the orbitals.

P orbitals are shaped like propeller blades with 2

lobes (3 types)

S orbitals are shaped liked spheres

s, p, d, f

Atomic Sublevel Orbitalsd orbitals are also shaped like propeller blades but

have 4 lobes (5 types)

Only exception is the dz orbital that has one ring shaped lobe.

s, p, d, f

Atomic Sublevel Orbitalsf orbitals have several different types of shapes,

each with 6 lobes

s, p, d, f

Atomic Sublevel OrbitalsEven though the orbitals get larger or have more lobes as the orbitals get farther from the nucleus, each and

every orbital can only hold up to 2 electrons.

Atomic Sublevel OrbitalsEach principal energy level always begins with an S

orbital. They just get larger, further from the nucleus.

1s1s

2s

Atomic Sublevel OrbitalsBeginning on the second principal level, three p orbitals

are used, after the s orbital is full.

1s1s

2s

Atomic Sublevel OrbitalsWith the p orbitals, one electron has to be in each p orbital, before any of the orbitals can gain a second

electron.

1s1s

2s

Hund’s Rule: Everyone gets one before anyone gets a second one

Atomic Sublevel OrbitalsOn the third principal energy level, the s orbital would be first, followed by three p orbitals, then up to 5 d orbitals

would be added, with the Hund’s Rule applying to the addition of electrons.

Hund’s Rule: Everyone gets one before anyone gets a second one

Atomic Sublevel OrbitalsOn the fourth energy levels, the s orbital would be first, followed by three p orbitals, then 4 d orbitals, and then

up to seven f orbitals.

Hund’s Rule: Everyone gets one before anyone gets a second one

Hydrogen’s Atomic Energy levelsSince hydrogen has only one electron, the electron can be

found in only one orbital, at any given time, while the other orbitals remain empty

Hydrogen’s Atomic Energy levelsWhen the hydrogen atom gains or loses energy, the electron travels through the sequence of orbitals.

The End