An Introduction to Chemistry

Chapter 11
Modern Atomic The

An Introduct
by Ma

eory

tion to Chemistry
ark Bishop

Chapter
Map



Atomic
Theory

•  To see a World in
And a Heaven in
Hold Infinity in the
And Eternity in an
William Blake

•  Thus, the task is n
no one has yet se
nobody has yet th
everybody sees.
Erwin Schrod

n a Grain of Sand
a Wild Flower
e palm of your hand
n hour
e Auguries of Innocence

not so much to see what
een, but to think what
hought, about that which

dinger

Ways to deal with
Complexity and Unce

•  Analogies In o
something of the
scientists often u
example, in some
vibrating guitar st

•  Probabilities
the uncertainty o
and motion, we r
electron probably
instead of where

ertainty

order to communicate
e nature of the electron,
use analogies. For
e ways, electrons are like
trings.

In order to accommodate
of the electron’s position
refer to where the
y is within the atom

it definitely is.

Guitar String
Waveform



Allowed Vibrations
for a Guitar String



Wave Character
of the Electron

•  Just as the inte
of a guitar string
intensity of the
electron vary at
outside the nuc

•  The variation in
electron charge
terms of a three
wave like the st
guitar string.

ensity of the movement
g can vary, so can the
negative charge of the
t different positions
cleus.
n the intensity of the
e can be described in
e-dimensional standing
tanding wave of the

Wave Character
of the Electron

•  Although both t
guitar string can
number of poss
certain wavefor

•  We can focus o
waveform of va
without having
actual physical

the electron and the
n have an infinite
sible waveforms, only
rms are possible.
our attention on the
arying charge intensity
to think about the
nature of the electron.

Waveform for
1s Electron



Other Allowed
Waveforms



1s Orbital



Particle Interpretatio
of 1s Orbital

on

2s Orbital

•  The 2s orbital
is larger than t
a node, which
orbital where t
decreases to z

for a hydrogen atom
the 1s orbital and has
is a region within the

the charge intensity
zero.

Cutaway of 1s
and 2s Orbitals



Ground State and
Excited State

•  Hydrogen atom
in the 1s orbita
their ground s

•  A hydrogen ato
in the 2s orbita
state.

ms with their electron
al are said to be in
state.

om with its electron
al is in an excited

Realistic and
Stylized 2py Orbital



2px, 2py, and 2pz
Orbitals



3d Orbitals



Other Allowed
Waveforms



Sublevels

•  Orbitals that ha
potential energ
and the same
same subleve

•  The sublevels
called subshe

ave the same
gy, the same size,
shape are in the
el.

are sometimes
ells.

Orbitals for Ground S
of Known Elements

States

Electron
Spin



Pauli Exclusion
Principle

•  No two electrons
same in all ways

•  There are four w
the same:

• Electrons can
energy level.

• They can be i
• They can be i
• They can hav

s in an atom can be the
s.
ways that electrons can be

n be in the same principal

in the same sublevel.
in the same orbital.
ve the same spin.

Ways to Describe
Electrons in Atoms

•  Arrows are added to
the distribution of ele
and the relative spin
is an orbital diagram

•  The information in o
described in a shorth
electron configurat
1s2 2s2 2

o an orbital diagram to show
ectrons in the possible orbitals
n of each electron. The following
m for a nitrogen atom.

orbital diagrams is often
hand notation called an
tion.
2p3

Electron
Configurations

•  The sublevels are f
the lowest overall p

•  No two electrons in
all ways. This is on
Exclusion Princip

•  When electrons are
energy, they prefer
and all electrons in
same spin. This is c

filled in such a way as to yield
potential energy for the atom.

n an atom can be the same in
ne statement of the Pauli
ple.

e filling orbitals of the same
r to enter empty orbitals first,
n half-filled orbitals have the
called Hund’s Rule.