Title: Electron Configurations Chapter 5 Chemistry-CP
1Electron ConfigurationsChapter 5Chemistry-CP
2Radiant Energy
- The understanding of how electrons behave comes
from studies of how light interacts with matter. - Light carries energy through space in the form of
waves and also in the form of extremely tiny,
fast moving particles. - Light has the properties of waves particles.
3Light as Waves
- Light waves are a form of electromagnetic
radiation - Electromagnetic radiation are energy waves
IMPORTANT ASPECTS OF WAVES Crest The top of a
wave Trough The bottom of a wave Amplitude
(A) The height of a waves crest (from origin
to crest) Wavelength (?) The distance between 2
consecutive crests or two consecutive
troughs Frequency (?) The number of waves that
pass a given point per second
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5Waves
- Light travels at the speed of light.
- The speed of light is constant, which means it is
always the same value 3.00 108 m/s - Because light moves at a constant speed,
wavelength frequency are inversely proportional
as per the following equation. - c ? ?
- c speed of light
- ? wavelength (lambda)
- ? frequency (measured in 1/s or s-1 or
Hertz (Hz)) -
-
6c ? ?
- What is the frequency of a wave having a
wavelength of 8.12 x 102 m? - A helium neon laser produces red light whose
wavelength is 633 nm. What is the frequency of
this radiation? - Calculate the wavelength of a radio wave with a
frequency of 9.31 106 s-1.
7THE ELECTROMAGNETIC SPECTRUM
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9Gamma Rays
- Generated by radioactive atoms, nuclear
explosions and supernova explosions - Can kill living cellsused for cancer treatment
- Used to sterilize medical equipment
10X-Rays
- Discovered by accident in 1895, when W.C.
Roentgen shielded a cathode ray tube with black
paper and found that a fluorescent light could be
seen on a screen a few feet from the tube (first
bone x-ray was of his wifes hand!) - Electrons shot at an element (such as tungsten or
molybdenum) with high energy can knock an
electron out of that atom, producing x-rays - Used for radiography, crystallography, astronomy,
airport security
11Ultraviolet Radiation
- Gets its name from the fact that it consists of
waves with frequencies higher than what humans
associate with violet light - Emitted from the sun, from black lights
- UV-B produces Vitamin D, too much DNA damage
collagen fibers, can cause sunburn, may lead to
cataracts - Some animals, insects, birds and reptiles can see
the near ultraviolet making certain flowers, etc.
brighter to them.
12VISIBLE LIGHT
- Portion of the electromagnetic spectrum that is
visible to the human eye - ROYGBIVViolet has the highest frequency
13Infrared
- Below red
- Heat radiation
- Emitted from humans at normal body temperature
- Military use (surveillance, night vision, homing)
- Short ranged wireless communication, weather
forecasting, remote temperature sensing - Purple white light get on cheaper digital cameras
(poor infrared filters)
14Microwaves
- Wireless LAN Bluetooth
- Radar Detectors, Air Traffic Control
- GPS
- The frequency of the waves used in microwave
ovens, 2500 megahertz, targets water, sugar fat
molecules - Thin, sharp metals can not handle the electric
current passing through them and may spark or
start a fire - Has never been conclusively shown that microwaves
have biological effects - http//www.youtube.com/watch?vUg8hSqkFUXY
- http//www.youtube.com/watch?vPIrd4172Czw
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16Radio Waves
- Transport information through the atmosphere or
space without wires - AM FM Radio, TV transmission, mobile phones,
military communications, wireless computer
networks
17Visible Spectrum
- Part of the electromagnetic spectrum
- Continuous Spectrum One color fades gradually
into the next. - Different colors have different wavelengths.
- The color of visible light with the largest
wavelength and lowest frequency is - The color of visible light with the shortest
wavelength and highest frequency is - The brightness of visible light is determined by
18- Radiation with the largest wavelength and lowest
frequency is - Radiation with the shortest wavelength and
highest frequency is - Radiation with frequencies greater than visible
light can pose health hazards because - Radiation with frequencies lower than visible
light are less harmful because
Aircraft Shipping Bands, Radio Waves
Gamma Rays
Have high enough energy to be capable of damaging
organisms
Do not have enough energy and pose no health
hazards
19What puzzled scientists about electromagnetic
radiation?
- Why do objects at different temperatures give off
different color light? - Why do different elements emit different colors
when heated?
20Plancks Theory
- Suggested that the energy emitted or absorbed by
an object is restricted to pieces of particular
sizes called quanta. - Substances can emit or absorb only certain
amounts of energy (so only certain wavelengths) - Showed that frequency and energy are directly
proportional
21Plancks Theory
Plancks Theory
- E h ?
- h Plancks constant 6.626 10-34 J?s
- Joule (J) S.I. Unit for Energy
What is the approximate energy of Ultraviolet
Light? What is the energy of radiation with a
wavelength of 290 nm?
How much energy is contained in a wave with a
frequency of 2 x 1016 Hz?
What is the frequency of a wave with an energy of
2.90 x 1022 J?
22Why cant you see quantum effects in the everyday
world around you?
- Plancks constant is very small, therefore, each
quantum of energy is very small - Quanta are too small to see in the everyday world
- Atoms are very small, so in relation to the atom,
quanta are significant
23The Photoelectric Effect
- Proposed by Albert Einstein
- In the photoelectric effect, electrons are
ejected from the surface of a metal when the
metal absorbs photons - Photon Quantum of light (a tiny particle of
light)
24The Photoelectric Effect
- When a photon strikes the surface of a metal, it
transfers its energy to an electron in a metal
atom - If the energy of the photon is too small for the
electron, the electron stays put - If the photon has enough energy, the electron
will escape the surface of the metal.
25The Photoelectric Effect
- Why is it easier for violet light (vs. red light)
to cause the photoelectric effect?
Violet light has a higher frequency and,
therefore, more energy than red light.
26Light has a Dual Nature
- A photon behaves like a particle but always
travels at the speed of light and has an
associated frequency and wavelength - In 1923, Arthur Compton showed that a photon
could collide with an electron - Light possesses the properties of both particles
and waves
27How can atoms gain or lose energy?
- Atoms can only gain or lose energy in a quantum
- Take a look through your spectral tube at the
emission tube at the front of the room. - How does what youre looking at demonstrate the
idea above?
28Line Spectrum
- A spectrum that contains only certain colors, or
wavelengths
- When heat or electricity is passed through an
atom, the atom absorbs the energy and then gives
off that energy in the form of light - The emitted light is unique for every element
- Atomic Emission Spectrum An atomic fingerprint
showing the emission line spectrum of that atom - Useful in identifying an element
29NIELS BOHR1913PLANETARY MODEL OF THE ATOM
Electrons move in defined orbits around the
nucleusjust as the planets move around the sun.
Orbit Region outside the nucleus where
electrons are found
30Bohrs Postulate
- Was applicable only to hydrogen
- Able to show that electrons move to higher energy
levels (excited states) when they absorb
radiation. - Electrons will immediately return to the lower
energy levels (ground state) by emitting energy
of a specific wavelength
31Light has a Dual Nature
- When light travels through space, it acts like a
wave - When light interacts with matter, it acts like a
particle - De Broglie predicted matter waves--that matter
should behave like waves and exhibit a wavelength - Clinton Davisson Lester Germer proved that
electrons (believed to be particles) were
reflected from a matter like waves - Mass of an object must be very small in order to
observe its wavelength
32Heisenberg Uncertainty Principle
- An electron is located by striking that electron
with a photon which bounces back to a detection
device - The electron is so small in mass that the
electron is moved by the collision - Proved a problem with Bohrs model You cannot
think of electrons moving in defined paths
because there is no way to prove the electrons
follow defined paths
33MODELS OVER TIME
34Quantum Mechanical Modela.k.a Wave Model
- Explains the properties of atoms by treating the
electron as a wave that has quantized its energy - Does not describe exact positions of the
electrons instead describes the probability that
electrons will be found in certain locations
around the nucleus
35Electron Cloud
An illustration that uses a blurry cloud to
illustrate the probability of finding an electron
in various locations around the nucleus.
(Determined by wave functions electron density
charts)
Areas of high electron density are the most
probable locations of the electrons.
Areas of low electron density are the least
probable locations of the electrons.
36Atomic Orbitals
- Region of space where the electron is located
- Have characteristic shapes, sizes and energies
- Do not describe how the electron actually moves
- The orbital occupied is determined by the amount
of energy of an electron
37s-Orbital
The s-orbital consists of 1 orbital on all 3
axes 1 orbital has a maximum of 2 electrons
38p-Orbital
The p-orbital can exist on 3 different axes (x, y
and z). Therefore there are 3 p orbitals. The
p-sublevels 3 orbitals can hold a maximum of 6
electrons (2 on each of the 3 orbitals).
A p-orbital has a dumbbell shape
39d-Orbital
There are 5 different orientations of a
d-orbital. The d-sublevels 5 orbitals can
hold a maximum of 10 electrons (2 electrons on
each orbital).
A d-orbital has a cloverleaf shape
40f-Orbital
An f-orbital has a complex shape
There are 7 different orientations of the
f-orbital. The f-sublevel can hold a maximum
of 14 electrons (2 for each orbital).
41Energy Orbitals
- Energy of electrons are quantized (exact)
- Principal Energy Levels or Principal Quantum
Number designates the distance of the electron
from the nucleus
Principal energy levels are divided into sublevels
42Sublevels
Sublevels of the atom are designated s, p, d f
The number of the energy level tells you how many
sublevels are present within that sublevel.
Another words Energy Level 1 has __________
Sublevel Energy Level 2 has __________
Sublevels Energy Level 3 has __________
Sublevels Energy Level 4 has __________
Sublevels The electrons address consists of its
principal energy level, its sublevel, and its
electrons within that sublevel
1
2
3
4
43SUBLEVEL s
Orbital Shape Max of electrons Region on Periodic Table Orbital Models
1 orbital s Sphere 2 Groups 1 2 (1st tower)
44SUBLEVEL p
Orbital Shape Max of electrons Region on Periodic Table Orbital Models
3 orbitals px py pz dumbbell 6 Groups 13-18 (2nd tower)
45SUBLEVEL d
Orbital Shape Max of electrons Region on Periodic Table Orbital Models
5 orbitals dxy dxz dyz dx2-y2 dz2 cloverleaf 10 Groups 3-12 (transition metals)
46SUBLEVEL f
Orbital Shape Max of electrons Region on Periodic Table Orbital Models
7 orbitals complex 14 Bottom 2 rows (inner-transition metals)
47Some Atomic Models
48More Models
49Example
Beryllium ______ protons, ______ electrons E-
Configuration 1s22s2
50Example
Oxygen ______ protons, ______ electrons E-
Configuration 1s22s22p4
51PRACTICE PROBLEMS
- Electron configurations for 3 different elements
are given below. Draw the atomic model of each
element and then identify the element. - Examples 1s22s1 1s22s22p3 1s22s22p63s23p4
- 1) 1s22s22p1 2) 1s2 3) 1s22s22p63s1
52Example
Boron ______ protons, ______ electrons E-
Configuration 1s22s22p1
53Examples
- Helium ______ protons, ______ electrons
- E- Configuration 1s2
54Examples
- Sodium ______ protons, ______ electrons
- E- Configuration 1s22s22p63s1
55Electron Spin
- Electrons spin either clockwise or
counterclockwise - The spinning creates a magnetic field
- Clockwise is like a magnet whose north pole is
pointing up - Counterclockwise behaves like a magnet whose
north pole is pointing down - Parallel Spins result in a net magnetic effect
- Opposite Spins cancel each other out
56Pauli Exclusion Principle
-1925, Austrian physicist-Wolfgang Pauli -States
that each orbital in an atom can hold at most 2
electrons and that these electrons must have
opposite spins (or be paired).
Sublevels Orbitals Max of e- s 1
2 p
3 6 d
5 10
f 7
14
57Electron Configuration
- The addresses of an atoms electrons
- Determined by distributing the atoms electrons
among levels, sublevels and orbitals based on a
set of principles - Orbitals from lowest to highest energy
- s? p ? d ? f
- Ground State The electrons are in the lowest
energy levels available
58How do electrons occupy energy levels?
- Aufbau Principle Electrons are added one at a
time to the lowest energy orbitals available
until all the electrons are accounted for - Pauli Exclusion Principle An orbital can hold a
maximum of 2 electrons that must spin in opposite
directions - Hunds Rule Electrons occupy equal-energy
orbitals so that a maximum number of unpaired
electrons results
59Orbital Diagrams
4p ____ ____ ____ 3d ____ ____ ____ ____
____ 4s ____ 3p ____ ____ ____ 3s ____ 2p
____ ____ ____ 2s ____ 1s ____
60What happens when an element in its ground state
is supplied with electricity or heat?
- Electrons may move to the excited state.
- Excited State Energy level attained when an
electron absorbs energy and jumps to a higher
energy level
Ground State
Excited State
61For each pair of orbital diagrams below, which
represents the ground state and which represents
the excited state of that atom?
4p ____ ____ ____ 3d ____ ____ ____ ____
____ 4s ____ 3p ____ ____ ____ 3s ____ 2p
____ ____ ____ 2s ____ 1s ____
4p ____ ____ ____ 3d ____ ____ ____ ____
____ 4s ____ 3p ____ ____ ____ 3s ____ 2p
____ ____ ____ 2s ____ 1s ____
Scandium
4p ____ ____ ____ 3d ____ ____ ____ ____
____ 4s ____ 3p ____ ____ ____ 3s ____ 2p
____ ____ ____ 2s ____ 1s ____
4p ____ ____ ____ 3d ____ ____ ____ ____
____ 4s ____ 3p ____ ____ ____ 3s ____ 2p
____ ____ ____ 2s ____ 1s ____
Magnesium
62What happens to the excited electron?
http//www.meta-synthesis.com/webbook/11_five/five
04.jpg
63Exceptions to the Aufbau Rule
- A half-full or full d sublevel will increase an
atoms stability - An electron may be removed from the s sublevel to
create a full or half full d sublevel
4p ____ ____ ____ 3d ____ ____ ____ ____
____ 4s ____ 3p ____ ____ ____ 3s ____ 2p
____ ____ ____ 2s ____ 1s ____
4p ____ ____ ____ 3d ____ ____ ____ ____
____ 4s ____ 3p ____ ____ ____ 3s ____ 2p
____ ____ ____ 2s ____ 1s ____
Cr
Cu
64Groups (also called Families)
- The vertical columns on the periodic table
- There are 18 groups, labeled with the numbers
1-18.
1
18
2
15
17
16
14
13
3
4
5
7
6
9
8
12
11
10
65Corresponding Regions on the Periodic Table
p-block Representative Elements Groups
13-18 Begins with Principal Energy Level
2 Contains 6 elements because each p sublevel can
hold up to 6 electrons
s-block Representative Elements Groups 1
2 Begins with Principal Energy Level 1 Contains 2
elements because each s sublevel can hold 2
electrons
f-block Inner Transition Metals lanthanides
actinides (bottom 2 rows) Begins with Principal
Energy Level 4 Contains 14 elements because each
f sublevel can hold up to 14 electrons
d-block Transition Metals Groups 3-12 Begins
with Principal Energy Level 3 Contains 10
elements because each d sublevel can hold up to
10 electrons
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67He
N
Ti
I
Fr
Ce
68Noble Gas Configuration Uses the symbol of the
noble gas in brackets to represent the inner
level electrons of an atom.
1s
2s
2p
3s
3p
3d
4p
4s
4d
5p
5s
Cd
5d
6p
6s
Ba
7p
7s
6d
4f
U
5f
69VALENCE ELECTRONS
- The electrons in the outermost energy level.
- Remember, the number in front of the sublevel
indicates the energy level - 1s22s22p6
- Sofind the highest energy level and add up all
the electrons in that level.
70EXAMPLES
- Calcium
- Aluminum
- Iodine
- Oxygen
- Iron
71ENERGY
Electrons with the most energy are located
farthest from the nucleus
Electrons with the lowest energies are located
close to the nucleus.
72Quantum
A quantum is the specific amount of energy needed
for an electron to move between energy levels.