II. Quantum Theory

A. Review of Atomic TheoryThomson

Discovered the electronsBohr

Determined electrons travel around the nucleus according to energy; electrons with lower energy are closer to the nucleus

Quantum Mechanical Model or Electrons Cloud ModelElectrons orbit the nucleus in

“clouds”; high probability of finding them somewhere along these paths

B. Electron ConfigurationElectron can jump multiple levels:

1 energy level (red light) 2 energy levels (green light) 3 energy levels (blue light) 4 energy levels (violet light)

B. Electron Configuration Cont.Electrons orbit in specific energy

levels.There are seven energy levelsLowest energy level = smallest

and the closest to the nucleusEach energy level has a specific,

limited number of electrons

C. Energy Levels, Sublevels, & Orbitals

The lowest energy level is n = 1

On the periodic table, each period (horizontal row) is an energy level

1234567

C. Energy Levels, Sublevels, & Orbitals

Each energy level has energy sublevels: s, p, d, f

Each energy sublevel has different number of orbitalsOrbitals: 3-D clouds where

electrons are found 90% of the time

Each orbital can hold 2 electrons

s sublevel = 1 orbital (2 electrons)

p sublevel = 3 orbitals (6 electrons)

d sublevel = 5 orbitals (10 electrons)

f sublevel = 7 orbitals (14 electrons)

C. Energy Levels, Sublevels, & Orbitals

ENERGY LEVELSSublevels (s, p, d, f)

Orbitals (1, 3, 5, 7)

Energy Level (n)

Sublevels # orbitals Max # e-

1 s 1 22 s

p13

2 6 (8 total)

3 spd

135

26

10 (18 total)4 s

pdf

1357

2610

14 (32 total)

III. Electron Configuration

A. Electron ConfigurationUnabbreviated method for describing the

arrangement of electronsExample: Helium (2 electrons)

Helium: 1s2

Energy LevelSublevel

# electrons

C. Energy Levels, Sublevels, & Orbitals

A. Electron ConfigurationExample: Neon (10 electrons)

Neon: 1s22s22p6

A. Electron ConfigurationExample:

Neon: 1s22s22p6

Tips to Remembering Electron ConfigurationSimply count, left to right, and know where s, p,

d, and f block are on the periodic table

B. Noble Gas ConfigurationAbbreviated electron configurationWrite full electron configuration for both Neon

(Ne) and Argon (Ar)Neon: 1s22s22p6

Argon:1s22s22p63s23p6

Argon: [Ne] 3s23p6