
Proposed model of the atom had a nucleus of
positive charge surrounded by a relatively large
area of empty space where electrons orbited

Did not propose an arrangement for the
electrons

Did not explain why the electrons were not
pulled into the nucleus (attraction of opposite
charges)

Light exhibits characteristics of waves

Wavelength (λ)

Frequency (ν)

amplitude

Different types

Each type has characteristic λ and ν

All parts travel with the speed of light
(c)… 3.00 x 108 m/s
𝑐 = λν

Microwaves are used to cook food and
transmit information. What is the wavelength
of a microwave that has a frequency of 3.44 x
109 Hz?
Now You Try:
Practice Problems 1 – 4 on page 140

Objects that are heated often give off a
characteristic color (red of stove burner,
white of light bulb)

View of light as a wave did not provide
an accurate explanation of why this
occurs

So….

Concluded that energy could only be
gained or lost in small, specific amounts
(like tiny packages)…called these
amounts quanta
E = hν

Another phenomenon that could not be
explained with light as a wave

When light of a certain minimum
frequency shines on a metal’s surface,
the metal will eject electrons (video)

Every object gets its color by reflecting a
certain portion of incident light. The color is
determined by the wavelength of the
reflected photons, thus by their energy. What
is the energy of a photon from the violet
portion of the Sun’s light if it has a frequency
of 7.230 x 1014 s-1?

Also called line spectra…not continuous

Set of frequencies of electromagnetic
waves emitted by an element

Not continuous

Unique for each element (like a
fingerprint)

Bohr
› Model stated that atoms orbit the nucleus in
definite paths (energy levels)
› Patterned this model after planets orbiting
the sun
› Electrons in a particular path (energy level)
have a fixed amount of energy…quantized
› Energy levels are analogous to the rungs on
a ladder

Based on a hydrogen atom

Assigned a quantum number (n) to each
orbit

As value of n increases, the amount of
energy increases

∆𝐸 = 𝐸 ℎ𝑖𝑔ℎ𝑒𝑟 𝑜𝑟𝑏𝑖𝑡 − 𝐸 𝑙𝑜𝑤𝑒𝑟 𝑜𝑟𝑏𝑖𝑡 =
𝐸 𝑝ℎ𝑜𝑡𝑜𝑛 = ℎ𝑣

Worked well for hydrogen

Did not explain the atomic spectra
produced by any other elements

Louis de Broglie (1892 – 1987)
› Recognized that electrons exhibited
characteristics of waves
› Recognized that light has properties of both
waves and particles
› Theorized that matter must be able to
possess qualities of waves and particles as
well

Predicts that all matter has wave
characteristics
ℎ
λ=
𝑚𝑣

States that it is fundamentally impossible
to know both the precise velocity
(momentum) and location of a particle
at the same time

Applies to all matter, but is useful only
with really small particles…like electrons

Schrodinger
› Revised Bohr’s model
› Mathematical equation to determine the
most likely place an electron would orbit the
nucleus
› Gives the probability of finding an electron in
a particular place within the atom
Used to describe orbitals
 Specify the properties of atomic orbitals
and the properties of the electrons in the
orbitals


First three derived from the Schrodinger
equation:
› Main energy level (n)
› Shape of orbital (l)
› Orientation of orbital (ml)

Fourth is the spin quantum number (ms)
› Describes the fundamental state of the
electron






Symbolized by n
Indicates the main energy level occupied
by an electron
Values are positive integers
As n increases, so does the distance from
the nucleus
More than one electron can have the
same n
Total number of orbitals for a given energy
level is given by n2
Each main energy level (except the 1st)
has different orbitals of different shapes
 Symbolized by l
 Indicates the shape of the orbital
 The number of orbital shapes possible for
each energy level is equal to the value
of n
 The values of l allowed are zero through
n-1

Depending on the value of l, the orbital is
assigned a letter
 0=s
 1=p
 2=d
 3=f

s = spherical
 p = dumbbell shaped
 d= complex
 f = way to complicated to explain…see
illustrations


Atomic orbitals are designated by the n
followed by the letter of the sublevel
Orbitals can have the same shape, but
different orientations around the nucleus
 Magnetic quantum numbers indicate
the orientation (ml)
 s orbitals have only one orientation
 p orbitals can extend along the x, y, or z
axis
 3 p sublevels (px, py, or pz)

Values for m sublevels correspond values
m = -1 m=0 and m=1
 5 different d orbitals…therefore 5
different orientations
 m=-2 m=-1 m=0 m=+1 m=+2
 7 different f orbitals….7 orientations

Electrons spin on an internal axis
 Can spin in one of two possible directions
 Spin quantum numbers can be +1/2 or 1/2
 A single orbital can hold a maximum of 2
electrons
 The electrons in a single orbital must
have opposite spins


Remember:
› All electrons can be described by a set of
quantum numbers
› No two electrons can have the same set of
quantum numbers

Aufbau Principle
› An electron will occupy the lowest energy orbital
that can receive it

Pauli Exclusion Principle:
› No 2 electrons in the same atom can have the
same set of quantum numbers

Hund’s Rule:
› Orbitals of equal energy are each occupied by
one electron before any orbital is occupied by a
second electron….All electrons in singly
occupied orbitals have the same direction of
spin (parallel spin)
Energy Level
Types of Orbitals
1
s
2
s, p
3
s, p, d
4
s, p, d, f
5
s, p, d, f
6
s, p
7
s, p
Orbital Type
# Sub-orbitals
s
1
p
3
d
5
f
7

Each sub-orbital can hold two electrons

The electrons in a sub-orbital must have
opposite spin
Type of Orbital
Max # electrons
s
2
p
6
d
10
f
14
Energy Level
Types of Orbital Max # of e-
1
s
2
2
s, p
8
3
s, p, d
18
4
s, p, d, f
32
5
s, p, d, f
32
6
s, p,
8
7
s, p
8

s, p, d, f blocks
1s
2s
3s
4s
5s
6s
7s
2p
3p
4p
5p
6p
7p
3d
4d
5d
6d
4f
5f

Carbon

Lithium

Sodium

Phosphorus

Neon

Write the complete electron configuration for:
› Helium
› Sulfur
› Magnesium
› Silicon
› Tin

Carbon

Lithium

Sodium

Phosphorus

Neon

Write the orbital notation for:
› Helium
› Sulfur
› Magnesium
› Silicon
› Tin

Use the noble gas that comes before the
element

Write the noble gas’s symbol in brackets

Continue with the electron configuration
from there

Calcium:
› Electron Configuration:
› Noble Gas Notation:

You try these:
a. Titanium
b. Silicon
c. Barium