Quantum Model of the Atom
The Bohr Model of the atom was incorrect
 Electrons do not orbit the nucleus

Quantum Model of the Atom
In the modern (quantum) model of the atom,
electrons are found in regions of space
called orbitals
 Orbitals are clouds of probability where
electrons are most likely to be found
 The shape of these clouds is the result of
plotting the solutions to very complicated
mathematical equations
 We will study 3 types: s, p, and d

Quantum Model of the Atom
There are 7 periods on the periodic table
 Each period represents the number of
energy levels in an atom
 Each energy level is represented by “n”

Structure of the Quantum Atom

Structure of the electron cloud

Principle energy levels (n)
 Obtained
from the Periodic Table
 Are whole numbers: 1, 2, 3, 4….

Sublevels
 s,

p, d, f
Orbitals – a MAX of two electrons are allowed in
each orbital for each value of n:
s
has one obital
 p has three
 d has 5
Quantum Model of the Atom
“s” orbitals
 Spherically
shaped
 There is one “s” orbital for each energy level
Quantum Model of the Atom
This is the probability diagram of an “s” orbital
n=1
This is a “1 s” orbital
n=2
This is a “2 s” orbital
Quantum Model of the Atom
“p” orbitals
 Dumbbell
shaped, with three different
orientations in space
 Starting with n = 2, there are THREE “p”
orbitals, px, py, pz for each energy level
Quantum Model of the Atom
“d” orbitals
 Dumbbell
shaped
 Starting with n=3, there are 5 “d” orbitals
Quantum Model of the Atom
How electrons fill their orbitals
Pauli Exclusion Principle
 Each
orbital can hold a maximum of TWO
ELECTRONS
Aufbau Principle
 Electrons fill orbitals that have the LOWEST
ENERGY FIRST
The Quantum Model of the Atom
Filling sequence:
1s<2s<2p<3s<3p<4s<3d
Each orbital can hold a maximum of 2 electrons
Quantum Model of the Atom
Example:
Hydrogen
 Has
one electron
 The first energy level to fill is the 1s orbital
 The one electron will fill in this orbital
 1s1
Energy
Level
Orbital
1
1s
Number of Electrons
in Orbital
Quantum Model of the Atom
Electron Configurations
 The
arrangement of electrons in an atom
 Filling pattern:
1s<2s<2p<3s<3p<4s<3d……..
Or use the following:
Quantum Model of the Atom
Filling Pattern
1s<2s<2p<3s<3p<4s<3d…
…..
Model of the atom with s and p
orbitals