Quantum Mechanical Model of the Atom

Getting familiar with the very, very small…

Vocabulary

QuantumAmount of energy required to move an electron

from it’s present energy level to another.

Like gravity the energy needed to change levels gets less the farther away from the nucleus you

get. Ex. See Pg 363

There is no fixed orbit like in the Bohr model. Instead, electron clouds provide a 90% probability that you’ll find an electron

somewhere in the cloud.

Electron Clouds

Vocabulary

Principle Quantum NumberN = 1, 2, 3, 4, etc… increases in energy

N is the number of sublevels. Ex. N=1, there is one sublevel

Regions where electrons can be found are called orbitals.

Vocabulary

Atomic Orbitalss, p, d, f

s orbitals are spherical.

p orbitals are dumbbell shaped in X, Y and Z planes

d orbitals are cloverleaf shaped in X, Y and Z planes

f orbitals are really complicated and difficult to visualize

VocabularyPrincipal Energy Level

# of sublevels

Type of sublevel N2 = # of orbitals

n = 1 1 1s (1) 12 = 1

n = 2 2 2s (1), 2p (3) 22 = 4

n = 3 3 3s (1), 3p (3), 3d (5)

32 = 9

n = 4 4 4s (1), 4p (3), 4d (5), 4f (7)

42 = 16

Total possible number of electrons in a principal energy level (n)

# of electrons = 2n2

Ex. 2 * (1)2 = 2, so in the 1st principal energy level there can only be 2 e’s.

Ex. 2 * (2)2 = 8, so in the 2nd principal energy level there can only be 8 e’s.

Vocabulary

Aufbau Principlee-’s enter orbitals of the lowest energy 1st.

Orbitals within a sublevel are always equal in energy.

S is always the lowest energy sublevel.

Beyond the 2nd energy level, there are interesting changes that happen with the overlapping of principle energy levels.

Aufbau orbital filling order

Vocabulary

Pauli Exclusion PrincipleAn atomic orbital may describe at most 2 e-’s

and they will have opposite spins.

Ex. or

Magnets come from the aligning magnetic domains, coming from electron spins

Vocabulary

Hund’s Rule When you’re filling orbitals, e-’s don’t want to

be paired unless they have to.

Like a family filling rooms. If there

is an empty room, then the electrons

will go there first.

Let’s PracticeSodium (Na)

Electron configuration: 1s2 2s2 2p6 3s1

Now draw the Aufbau Diagram of Sodium (Na).

Use diagram on page 367 in your book to set it up.

Let’s PracticeChlorine (Cl)

Electron configuration: 1s2 2s2 2p6 3s2 3p5

Now draw the Aufbau Diagram of Chlorine (Cl).

Use diagram on page 367 in your book to set it up.