Atomic Structure
The Atom
 Smallest form of an element that still retains
that elements properties
 Basic building block of matter
 Made of:
Protons
Neutrons
Electrons
The Atom
Composed of:
Nucleus
Electron Cloud
The Nucleus
Positively charged
Protons and neutrons
Protons – positively
charged
Neutrons – neutrally
charged
Neutrons act like glue
The Electrons
 Negatively charged
 Occupy the “Electron cloud”
surrounding the nucleus
 Arranged into shells or orbitals
 Electrons are NOT moving in
perfect orbits around the nucleus.
The electron movement is
unpredictable
 Cloud gives us approximate
location of where electrons are
Subatomic Particles
Location
Charge
Mass
Protons
Nucleus
Positive (+)
1 amu
Neutrons
Nucleus
Neutral
1 amu
Electrons
Electron Cloud
Negative (-)
0.00054 amu
Special Fact
Number of protons
determines the identity of
the element
Electron cloud takes up
99.9999999% of the
volume of the atom
Properties of Atoms
Atomic Number
Mass Number
AverageAtomic Mass
INSIDE THE SQUARES…
Atomic Number
 Number of protons in the nucleus of an atom
 Each element has its own specific atomic number
 In a NEUTRALATOM, this is also the number of
electrons
(Average) Atomic Mass
 An average mass of each of the different isotopes
found for that element in nature
 For example, Chlorine has 2 different isotopes
 Each one has 17 carbons and a different number of
neutrons (This is what an isotope is. More on that later)
 If you take the average atomic mass of every
single carbon atom that
exists, the average mass
will be 35.453 amu
Mass Number
 Mass number is the mass of a SPECIFIC isotope of an
atom.
 It is the SUM of the protons and neutrons in the nucleus
 Mass Number = (# of neutrons) + (# of protons)
Mass Number = Atomic Mass
It is not the average unless we sayAVERAGE
 How do we find # of
neutrons?
So how do I know what the
Mass Number is?
I will tell you. One of two ways:
1) Give you the mass number or the neutrons in a table.
If I don’t give it to you, get the rounded # off the PT
2)Tell you in the symbol .
A) Isotope Notation:
B) Isotope Name:
Sodium-23
Figuring out some element parts…
Element
Boron-11
Symbol
Atomic #
Protons
Neutrons
Mass #
B
Carbon -12
6
Magnesium-23
12
Copper-64
29
6
23
35
20
Figuring out some element parts…
Element
Symbol
Atomic #
Protons
Neutrons
Mass #
Boron-11
B
5
5
6
11
Carbon -12
C
6
6
6
12
Magnesium-23
Mg
12
12
11
23
Copper-64
Cu
29
29
35
64
?
?
?
20
?
?
Isotopes and Ions
Isotopes
 Isotopes: atoms of the same element
that have different numbers of
neutrons
 Two isotopes of an element will have
the same atomic number, but different
mass numbers (and atomic masses)
CARBON (above right)
1. What is the mass number to the left?
2. What is the mass number to the right?
3. What is the atomic number to the left?
4. What is the atomic number to the right?
Isotope Example
So, which of the following represent isotopes of
the same element?
#1
234
92
X
#2
#3
#4
234
235
238
93
X
X
92
Which element are these isotopes of?
92
X
Isotope Notation
Write the symbol with the mass
number on top and the atomic number
on the bottom
Example:
Isotope Example
Naturally occurring carbon consists of three isotopes,
14N, 15N, and 16N. State the number of protons,
neutrons, and electrons in each of these carbon atoms.
14N
7
#P
#N
#E
15N
7
16N
7
Ions
 IONS are charged atoms (or groups of atoms) that have a
positive or negative charge.
 Ions differ in the number of electrons
 For NeutralAtoms :
 Number of electrons = number of protons
 For Ions :
 protons the same, electrons are different
 Either lost or gained electrons
 Examples:
 NeutralAtom: Na, Ca, I, O
 Ion: Na+ Ca+2 I- O-2
IONS
 Taking away an electron from an atom gives a
positive charge because there are now more
protons
 Called a CATION
 So if the Mg atom to the right
loses 2 electrons, it becomes Mg2+
IONS
 Adding an electron to an atom gives a negative
charge because there are now more electrons
 Called an ANION
 So if the F atom to the right
gains 1 electron, it becomes F-
Ion Practice
State the number of protons, neutrons, and electrons in each of
these ions.
16O -2
41Ca +2
39 K+
19
#p+
#no
#e-
8
20
Electron Arrangement
Energy Levels
 Electrons that are closer to
nucleus have lower energy
 Further away = Higher energy
 So the further away from the
nucleus an electron is, the more
energy it has
 The electron cloud is organized
into shells.
 Each shell has a max. number of
electrons it can hold
# of Electrons in Each Energy Level
 1st Level = 2 electrons
 2nd = 8 e 3rd = 18 e 4th = 32 e-
 Electrons must occupy the lowest energy level or
orbital first
Bohr Diagrams
 Bohr Diagrams show each of the energy levels of the
atom
 Show every electron that the atom has orbiting around it.
 These electrons are organized into the different shells or
orbital levels
 1st level - 2 electrons
 2nd level - 8 electrons
 3rd level - 18 electrons
Examples:
Bohr Diagrams: You Try
 Draw me the Bohr Diagram of each of the following:
H
B
F
Si
Valence Electrons
 Electrons in outermost shell = valence electrons
 Determine the properties of the element
 Will it bond with other elements?Which ones?Valence
electrons tell us the answers.
 Each column (except for the transition metals) has
a set number of valence electrons
YOU-TRY!
 Use the group number above the column to
determine the number of valence electrons.
 Sodium – (Na)
1 valence electrons
 Boron – (B)
3 valence electrons
 Chlorine – (Cl) 7 valence electrons
 Neon – (Ne)
8 valence electrons
Lewis Dot Diagrams
 Uses the symbol of the element and dots to
representVALENCE electrons
Lewis Dot: How To…
 Write the symbol of the element
 Figure out how many valence electrons it has
 Each side of the symbol can only hold 2 electrons
 1 dot = 1 electron
 Each side must get one electron before any side can get 2
 Max Number = 8 dots for 8 electrons
 (You can’t have more than 8 electrons on the outside row)
NUCLEAR ENERGY!
DAY 1: (RADIATION, FISSION, FUSION)
Nucleus Stability

Stability of the nucleus depends on the
nuclear forces that act between protons
and neutrons
 Protons
repel
each other
 Protons attract
neutrons because
of the strong
nuclear force
Nucleus Stability

Nuclei with too many protons or neutrons
are unstable.
 If
an atom is unstable, it will try to become
stable by splitting into two smaller atoms.
 Nuclei with more than
83 protons are
ALWAYS unstable
Nucleus Stability

Essentially, nuclear stability is based on
the arrangement of the protons and
neutrons in the nucleus
The
more efficient and tightly packed the
nucleus orientation is, the more stable the
nucleus is
FISSION

Fission is the process where a nucleus splits
into two or more smaller fragments, releasing
neutrons, and energy
 Nucleus
must be large for this to happen
Ex: Uranium-235
Uranium-235 only makes up 0.7% of the Uranium in the world
The rest is stable Uranium-238 – The largest naturally occurring element
Done
in nuclear power plants and atomic bombs
FISSION
Neutrons are used
as bullets to break
apart the uranium235 nucleus.
 3 Products form

 Fission
Products:
Barium and Krypton
 3 Free Neutrons
 Energy is released
FISSION: Multiple Pathways

There are a multiple pathways for Uranium to decay


The pathway we concentrate on involves Ba and Kr products
In any case, there will always be 3 products, regardless of
pathway.



Fission Products
2-3 Free Neutrons
Energy is released
Chain Reactions

Chain Reaction: The 3 neutrons that are
released from fission start an additional
fission reaction in a different U-235 nucleus
 This
produces more neutrons and repeats.
 The process may be
 controlled
(nuclear power plants/submarines)
 uncontrolled (nuclear weapons).

Video – Chain Reaction with M Traps (3
Chain Reactions
FISSION ENERGY
Hahn and Strassman found that the overall
mass decreases after the reaction happens.
 The missing mass changed into energy

E
= mc2
 Energy = mass * speed of light2
 Speed

of light = 300,000,000 m/s
Sooo…
= mc2
 E = (1kg) * (300,000,000m/s)2
 E = 90,000,000,000,000,000 Joules
 E = 9x1016 joules
E
FISSION ENERGY

Converting 1 kg of Uranium-235 into energy.





Energy produced burning 1 kg of coal (not using E = mc2)




E = mc2
E = (1kg) * (300,000,000m/s)2
E = 90,000,000,000,000,000 Joules
E = 9x1016 joules
E = 31,000,000 joules
E = 3.1 x 107 joule
So: 1kg of Uranium 235, undergoing fission, will produce over
1 trillion times the energy of 1kg of coal being burned
Video: Fission Reactions (2 min)
FUSION
Two lighter nuclei combine to form a heavier
nucleus
 Start with:

2

Hydrogen isotopes (deuterium and tritium)
End with with:
1
Helium atom
 1 Neutron
 Energy

Occurs in stars/the sun
ENERGY IN FUSION



A large amount of energy is
needed to create very high
temperatures so that the
isotopes can be hurled at
each other and overcome the
tendency of positively
charged nuclei (the Hydrogen
isotopes) to repel each other.
This is why FUSION occurs in
Stars and our Sun
Video – Sun’s Energy (6
A Recap

And don’t forget that both release energy!
ENERGY COMPARISONS

Finding the elements: Radiation (12 min)
Starts
at 1:44:30…
Nuclear Radiation

Radiation:
Emission
of energy or particles from an
unstable decaying atom
Nuclear Radiation

Background radiation:
that arises naturally from cosmic rays from
radioactive isotopes in the soil and air
 Radiation
 Continuously
exposed to radiation from natural sources:
 sun, soil, rocks, plants
than 80% of radiation exposure due to natural
sources
 More
 You
can change your exposure based on many things:
 Air travel, where you live, smoking, x rays, job, etc…
Nuclear Radiation

Radiation comes in 3 forms:
Alpha
particles
Beta particle
Gamma particle
NUCLEAR ENERGY!
DAY 2: (USES, PROS, CONS)
Ways We Use Nuclear Energy
Nuclear Medicine
 Nuclear Weapons
 Nuclear Power

 Nuclear
power plants
 Nuclear submarines
Nuclear Medicines
Nuclear Medicine: The use of radioactive
substances in the diagnosis or treatment
of diseases
POSITIVE:
 Check body systems to make sure working properly


Radiopharmaceuticals are taken orally and then a “gamma
camera” captures images of emitted radiation from inside body
Nuclear Medicine Therapy- Intravenous or oral
administered drug

Used to treat conditions such as hyperthyroidism, thyroid cancer,
and blood disorders
Nuclear Medicines
Nuclear Medicine: The use of
radioactive substances in the
diagnosis or treatment of diseases
NEGATIVE:
 Produces mild radiation, so it can
damage/cause cancer in healthy cells
 Nuclear waste must be stored
 VERY expensive to set up in a facility
Nuclear Weapons







This is a “Uncontrolled Fission Reaction”
Tremendous amounts of energy available from small
amounts of fuel
 can be “smuggled easily.”
Tremendous amount of destruction
Contamination of the environment for very long amounts of
time
Video: Top 10 explosions ever http://www.youtube.com/watch?v=yRRGaxx8Zf4
(4 min)
Video: Effects of a nuclear bomb http://www.youtube.com/watch?v=Aza2wopCFY (4 minutes)
Video: Time lapse of every nuclear explosion ever
http://www.youtube.com/watch?v=gJe7fY-yowk (5 min)
Nuclear Weapons
Nuclear Reactor: How It Works
Nuclear Reactor: This is a Controlled
Nuclear Fission Reaction
Nuclear Reactor: This is a Controlled
Nuclear Fission Reaction
Nuclear Reactor: How it works
Video (5 min) http://www.youtube.com/watch?v=PKNbwcIaGng
Nuclear Energy in 4 easy steps:

1) A Fission chain reaction begins while the fuel
rods are in the water
The
amount of fission is controlled by lead Control
Rods
2) The water heats up and changes to steam
 3) The steam turns a turbine
 4) The turbine turns a generator, forming
electricity

The steam is then cooled down in a cooling tower
 The spent fuel rods need to be stored for
hundreds/thousands of years

Nuclear Energy:

Used Fuel Rods
Nuclear Energy: Where Are They

65 Nuclear Power Plants in the United States
 Produce
19.6% of our energy (2008)
 SC has 4 plants, producing over ½ of our energy
Nuclear Energy BENEFITS
Tremendous amounts of
energy available from
small amounts of fuel
 No air pollution of
greenhouse gasses from
the burning of fossil fuels
 Can be used anywhere
 Abundance of fuel
 Non-reliance on fossil fuel

NUCLEAR ENERGY NEGATIVES:
Can cause thermal pollution to
water systems (if you put the hot
water back into rivers)


Waste must be stored until it is no longer radioactive –
can be a very long time.
Improper handling of nuclear materials
Power plant failure – radioactive explosions

Fukushima Explained - http://www.youtube.com/watch?v=rBvUtY0PfB8 (5 min)

