Download Chapter 4 Greek Idea Thomson`s Model Rutherford`s Model Bohr`s

Greek Idea
 Democritus
Chapter 4
Electrons in Atoms
Thomson’s Model
 Discovered
electrons
 Atoms were made of
positive stuff
 Negative electron
floating around
 “Plum-Pudding”
model
and
Leucippus
 Matter is made up
of indivisible
particles
 Dalton - one type
of atom for each
element
Rutherford’s Model
 Discovered
dense
positive piece at
the center of the
atom
 Nucleus
 Electrons moved
around
 Mostly empty
space
Bohr’s Model
don’t the electrons fall into the
nucleus?
 Move like planets around the sun.
 In circular orbits at different levels.
 Amounts of energy separate one
level from another.
Bohr’s Model
 Why
Nucleus
Electron
Orbit
Energy Levels
1
The Quantum Mechanical
Model
Bohr’s Model
Increasing energy
Fifth
Fourth
Third
Second
First
Nucleus
 Further
away
from the
nucleus means
more energy.
 There is no “in
between”
energy
 Energy Levels
The Quantum Mechanical
Model
 Things
that are very small
behave differently from things
big enough to see.
 The quantum mechanical
model is a mathematical
solution
 It is not like anything you can
see.
The Quantum Mechanical
Model
 The
atom is found
inside a blurry
“electron cloud”
 A area where there is
a chance of finding
an electron.
 Draw a line at 90 %
 Energy
is quantized. It comes in chunks.
quanta is the amount of energy needed to
move from one energy level to another.
 Since the energy of an atom is never “in
between” there must be a quantum leap in
energy.
 Schrodinger derived an equation that
described the energy and position of the
electrons in an atom
A
The Quantum Mechanical
Model
 Has
energy levels for
electrons.
 Orbits are not circular.
 It can only tell us the
probability of finding
an electron a certain distance from
the nucleus.
Atomic
Orbitals
Quantum Number (n) = the
 Principal
energy level of the electron.
each energy level the complex
math of Schrodinger’s equation
describes several shapes.
 These are called atomic orbitals
 Regions where there is a high
probability of finding an electron.
 Within
2
P orbitals
S orbitals
 Start
1
s orbital for
every
energy
level
 Spherical
shaped
 Each s orbital can hold 2 electrons
 Called the 1s, 2s, 3s, etc.. orbitals.
at the second energy level
different directions
 3 different shapes
 Each can hold 2 electrons
3
P Orbitals
D orbitals
 Start
at the second energy level
 5 different shapes
 Each can hold 2 electrons
F orbitals
F orbitals
 Start
at the fourth energy level
 Have seven different shapes
 2 electrons per shape
3
By Energy Level
Summary
# of
Max
shapes electrons
Starts at
energy level
s
1
2
1
p
3
6
2
d
5
10
3
f
7
14
4
 First
Energy Level
 only s orbital
 only 2 electrons
2
 1s
By Energy Level
 Third
energy level
p, and d
orbitals
 2 in s, 6 in p, and
10 in d
2 6 10
 3s 3p 3d
 18 total electrons
Increasing energy
 s,
7s
6s
5s
5p
4p
4d
4s
3p
3s
2p
2s
energy
level
 s,p,d, and f
orbitals
 2 in s, 6 in p, 10
in d, ahd 14 in f
2 6 10 14
 4s 4p 4d 4f
 32 total electrons
6d
5d
3d
Energy
Level
 s and p orbitals
are available
 2 in s, 6 in p
2 6
 2s 2p
 8 total electrons
By Energy Level
 Fourth
7p
6p
 Second
 Any
more than
the fourth and not
all the orbitals will
fill up.
 You simply run
out of electrons
orbitals do
not fill up in a
neat order.
 The energy levels
overlap
 Lowest energy fill
first.
Electron Configurations
5f
4f
 The
 The
way electrons are arranged in
atoms.
 Aufbau principle- electrons enter the
lowest energy first.
 This causes difficulties because of the
overlap of orbitals of different energies.
 Pauli Exclusion Principle- at most 2
electrons per orbital - different spins
1s
4
Electron Configuration
Rule- When electrons occupy
orbitals of equal energy they don’t
pair up until they have to .
 Let’s determine the electron
configuration for Phosporus
 Need to account for 15 electrons
Increasing energy
 Hund’s
7s
6s
5s
6d
5d
5p
4d
4p
3p
2s
4f
3d
4s
3s
5f
Increasing energy
Increasing energy
7p
6p
 The
next electrons
go into the 2s orbital
2p
 only 11 more
7s
6s
5s
4s
3s
2s
1s
5d
4d
4p
3p
3s
2s
7s
6s
5s
3d
first to electrons
go into the 1s orbital
2p
 Notice the opposite
spins
 only 13 more
2s
 The
7p
6p
6d
5d
5p
4d
4p
4s
3s
5f
4f
5f
4f
3d
3p • The next electrons go
into the 2p orbital
2p
• only 5 more
1s
7p
6p
6d
5d
5p
4p
4d
3d
3p • The next electrons go
into the 3s orbital
2p
• only 3 more
5f
4f
Increasing energy
Increasing energy
1s
6d
4s
1s
7s
6s
5s
7p
6p
5p
7s
6s
5s
4s
3s
2s
1s
7p
6p
6d
5d
5p
4p
4d
5f
4f
3d
3p • The last three electrons
go into the 3p orbitals.
2p • They each go into
seperate shapes
• 3 upaired electrons
• 1s2 2s22p63s 23p3
5
The easy way to remember
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
• 1s2
• 2 electrons
Fill from the bottom up
following the arrows
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
• 1s2 2s2 2p6 3s2
• 12 electrons
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
• 1s2 2s2 2p6 3s2
3p6 4s2 3d 10 4p6
5s2
• 38 electrons
• 1s2 2s 2
• 4 electrons
Fill from the bottom up
following the arrows
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
Fill from the bottom up
following the arrows
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
Fill from the bottom up
following the arrows
• 1s2 2s 2 2p 6 3s2
3p 6 4s2
• 20 electrons
Fill from the bottom up
following the arrows
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
• 1s2 2s 2 2p 6 3s2
3p 6 4s2 3d10 4p6
5s2 4d 10 5p 6 6s2
• 56 electrons
6
Fill from the bottom up
following the arrows
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
• 1s2 2s2 2p6 3s2
3p6 4s2 3d 10 4p6
5s2 4d10 5p6 6s2
4f14 5d10 6p6 7s2
• 88 electrons
Fill from the bottom up
following the arrows
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
• 1s2 2s 2 2p 6 3s2
3p 6 4s2 3d10 4p6
5s2 4d 10 5p 6 6s2
4f 14 5d 10 6p 6 7s2
5f 14 6d 10 7p 6
• 108 electrons
Orbitals fill in order
Lowest
Exceptions to Electron
Configuration
energy to higher energy.
Adding electrons can change the
energy of the orbital.
Half filled orbitals have a lower
energy.
Makes them more stable.
Changes the filling order
Write these electron
configurations
Chromium is actually
 Titanium - 22 electrons
 1s22s22p63s23p64s23d2
1s 22s22p63s23p64s13d5
 Vanadium - 23 electrons
1s22s22p63s23p64s23d3
This
 Chromium - 24 electrons
 1s22s22p63s23p64s23d4 is
 But
Why?
gives us two half filled orbitals.
Slightly lower in energy.
The same principal applies to copper.
expected
this is wrong!!
7
Copper’s electron
configuration
 Copper
has 29 electrons so we
expect
 1s22s22p63s23p64s23d9
 But the actual configuration is
 1s22s22p63s23p64s13d10
 This gives one filled orbital and one
half filled orbital.
 Remember these exceptions
8