Transcript Notes #3

Chemistry
Chapter 5
Notes #3
Rules

Neils Bohr
 Added
on to Planck’s and Einstein’s theories
• Lowest available energy state of an atom
• Ground State
• When an atom gains energy =
• Excited State
 This applies to the Atomic emission spectra!!
Rules

Heisenberg Uncertainty Principle
It is fundamentally impossible to know
precisely both the velocity and the
position of a particle at the same time
 Ex. Blades of a running fan (on high)
 That is how the electrons are traveling

Rules

Aufbau Principle
 Electrons “fill”
atoms starting
at the lowest
energy and
moving out to
higher amounts
of energy
 Excited vs.
Ground State
Rules

Pauli Exclusion Principle
 A max of 2 electrons
will occupy a single
orbital
 The electrons have
opposite spins

The opposite spin
requirement is born out
of quantum physics….2
electrons cannot have
the same quantum
number – therefore they
must have opposite
spins
Rules

Hund’s Rule

Single electrons with
the same spin occupy
each orbital (of a
multi-orbital sublevel)
before additional
electrons with
opposite spins
occupy the same
orbital.

Remember – Electrons are
all negative – so they repel
each other –meaning they
take as much space as
they can…
“Blocks on the table!
Noble gas Configuration


Shorthand to electron configuration
Steps:
 Find the noble gas that comes directly
before the element you are looking at
 Put the chemical symbol of the noble gas
in brackets
 Then, continue the electron configuration
at the beginning of the row immediately
following the noble gas
Noble gas Configuration
Element
Atomic
#
Na
11
Ca
20
Sr
38
P
15
Br
35
I
53
e- conf
Noble gas Conf.