Transcript FACT: - Moscrop Chemistry

FACT:
Chemical reactions
happen because
electrons are shared or
transferred from one
substance to another
MAX NUMBER OF ELECTRONS
IN AN ENERGY LEVEL
ENERGY LEVEL
MAX # OF ELECTRONS
1
2
3
4
5
2
8
18
32
50
Write a mathematical equation that
allows us to predict the Max # if we
know the energy level (n)
Max # = …n…
ENERGY LEVEL
MAX # OF ELECTRONS
1
2
3
4
5
2
8
18
32
50
Equation to calculate
Max # of e
2
2n
Where n is any energy level
On the Back of your Max # of
Elections Sheet
Bohr Models
Draw the Bohr Structures
for elements 1-18
WHITEBOARDING
Bohr Models
Draw the Bohr Structure
for Z=19 (Potassium)
Catalyst
Draw the Bohr Structure
for Z=19 (Potassium)
Obviously something is
wrong…because the
electrons fill in an
unexpected order.
We need a more
complicated system!
There are 4 Quantum
#s and those #s are
used to describe where
an electron is likely to
be found at any given
time
This is a lot like being
able to use four “places”
to describe EXACTLY
where Mr. T should be
at 8:00AM on Friday.
The first number we
already know…
The Principle
Quantum #
(b.k.a. The NRG level)
st
1
Quantum #
Principle Quantum #
Specifies the energy
level that the electron
is on
But this doesn’t
explain why K’s last
electron goes into the
th
4 energy level instead
rd
of the 3
nd
2
Quantum #
Specifies the shape of
the sub-energy level
s and p Sub Energy Levels
III. Quantum Mechanical Model: Atomic Orbitals
E. Shapes of orbitals
d orbitals
ORBITAL
Space occupied by
a pair of electrons
Four Sub-Energy Levels
Sub NRG
Level
s
Shape
Sphere
Max # of
electrons
2
# of
Orbitals
1
p
Dumbbell
6
3
d
4-Lobed
10
5
f
6-8 Lobed
14
7
Sub-Energy Levels
So why do
electrons fill in
like they do?
i.e. why is K’s last electron
th
in the 4 NRG level?
2 Factors Influencing
Electron Placement
1.Energy Level
- Closer to nucleus=easy
2. Subenergy level (shape)
- spdf
Electron
Configuration
A detailed way of
showing the order in
which electrons fill in
around the nucleus
Electron Configuration
Symbols
-
3
5f
Energy Level
# of e in
sub-energy
level
Sub-Energy
Level
Electron Configuration PT
K
Bohr
Models
vs. e
Configs
2
2
6
1
6
2
K:1s 2s 2p 3s 3p 4s
e config
Write the
for:
1
H: 1s
2
He: 1s
2
1
Li: 1s 2s
2
2
6
2
6
1
K: 1s 2s 2p 3s 3p 4s
Again…
Why are we
concerned so
much about
electrons?
So do we really
need to know
about all of the
electrons?
e
configs with
the NGSC
represent which
electons?
Valence Electrons
Electrons in the
outermost energy
level
(involved in chemical reactions)
Noble Gas Shortcut
2
2
6
2
6
1
1s 2s 2p 3s 3p 4s
K:
1
K: [Ar] 4s
So what is different?
Aufbau
Principle
All lower energy sublevels
must be full before high
energy sublevels begin
filling in
Steps for writing NGSC
1. Write the noble gas
preceding the desired
element [in brackets]
2. Carry on as usual
With only the first two
Quantum #s, do we have
as much information as
possible as to where the
electrons are likely to be
found?
rd
3
Quantum #
m or magnetic Q#
Specifies the
orientation of an
orbital in space
th
4
Quantum #
s or spin Q#
Spin of an electron on
its own axis
Quantum Review
st
1
Q#: Energy Level
nd
2 Q#: Shape of sub
rd
3 Q#: Orientation of Orbital
th
4 Q#: Spin of e
Quantum Review
Principle (n): 1, 2, 3, 4, …
Azimuthal (l): 0, 1, 2, 3
Magnetic (ml): …-2, -1, 0, 1, 2
Spin (ms): +1/2 or -1/2
Pauli Exclusion
Principle
No 2 electrons can
have the same set of 4
quantum numbers
Arrow-Orbital
Diagrams
A way to show
orbital filling, spin,
relative energy
Hund’s Rule
Most stable
arrangement of
electrons is the one with
the maximum number of
unpaired electrons
Energy
Arrow-Orbital Diagrams
3d
4s
1s
2s
2p
3s
3p
Lewis Electron
Dot Diagrams
The easiest way to
represent the # of
valance electrons
Steps for writing
electron dot diagrams
1. Write the element’s symbol
2. Write out e config
-s
3. Count # of valence e (1-8)
4. Place same # of dots as e
around symbol
Order to fill in an
e dot
3 6
4
7
Bm
5
8
1
2
What up?
Bm
1
2
Who do 1 and
2 represent?
Why do 1 and 2 fill in on
the same side?
What up?
4
7
3 6
Bm
5 8
Who do 3-8
represent?
Why do 3,4,5 and 6,7,8
fill in on different sides?
What up?
4
7
3 6
Bm
5 8
1
2
Why will you
never have
more than eight
dots?
Examples of Lewis Electron Dots
What is different between the
dot diagrams below and the
ones that we’ve been doing?
Our way accounts for
Quantum #s, this way doesn’t!
Flame Tests
Certain elements
emit specific
wavelengths of light
when the electrons
fall from outer
energy levels back
to their ground
state.
The Electromagnetic Spectrum
Line Spectra of Excited Atoms
• Excited atoms emit light of only certain wavelengths
• The wavelengths of emitted light depend on the
element.
H
Hg
Ne