Nonrenewable Energy: Nuclear

Energy Part 2

What do you know about Nuclear Chemistry?

http://ed.ted.com/lessons/radioactivity-expect-the-unexpected-steve-

weatherall

I. Radiation

• Radiation = any ____________________ through space

Example: electromagnetic radiation

• Not all radiation is dangerous!

o How powerful or dangerous radiation is depends on two

factors: the wavelength and the energy

The _________the ___________, the ______ the _______

• The_______ the _______, the more stuff it can pass

through = the most dangerous!

Example: ______ and ____________have the

____________ so ______________

movement of energy

shorter wavelength higher energy

most dangerous

X-rays Gamma rays most energy

higher energy

• Radiation can be categorized into two groups: nonionizing or

ionizing

• Therefore, _________ radiation is _______________

Nonionizing Ionizing

• ______________ radiation:

radio, microwave, infrared,

visible light, some UV rays

• Causes ___________________

faster or _____________

• ______________ radiation:

some UV rays, X-Ray, Gamma

• Causes ________________

atoms and molecules,

_____________

• Gamma rays can even break up

an atom’s nucleus

Lower energy

molecules to vibrate

give off light

Higher energy

electrons to leave

creating ions

ionizing more dangerous

II. What is Nuclear Chemistry?

• Nuclear Chemistry = The study of reactions that are caused by a

___________________of an atom

• Unlike regular chemical reactions where elements simply re-arrange, in

nuclear reactions ____________are ________!

o _________ in nucleus ________ = ________________

• When a nucleus break ups it releases a lot of energy and that energy is what

is used in nuclear energy sources

o Recall: nuclear energy is a ______________ energy source

While nuclear energy does use elements that can be found in nature,

the element most commonly used in a nuclear power plant (uranium-

235) is very rare and there is a limited amount of it

change in the nucleus

new elements formed

Protons change different element

nonrenewable

Fill in each circle with one of the following:

New element

Ion

Isotope

Molecule/compound

• Why does this happen? Why does the nucleus of an atom change? It

comes down to stability. Some isotopes of elements are stable,

some are unstable

o Nuclear Stability= the larger (more massive) a nucleus is, the

harder it is for it to stay together

• When _______ are __________, they emit energy in the form of

radiation = they are ____________

• When a nucleus is radioactive, it gives off decay particles and

_________________________________in order

_____________________. This process is known as

_____________________________.

isotopes unstable

radioactive

changes from one element to another

to become more stablenatural decay or transmutation

III. Modes of Decay

• Radioactivity (radioactive decay)= the ________________ of the

_________ of an unstable atom in order to become more stable

o Results in the emission or ________ of __________________

• There are different modes or types of decay—different particles that

are released

• Modes of Decay (See Table ___)O

decay or break-up

nucleus

release particles and/or energy

Type of

Decay

Symbol Charge Mass Penetration

Strength

𝟒

𝟐He or

𝟒

𝟐α +𝟐

𝟎

−𝟏e or

𝟎

−𝟏β

𝟎

+𝟏e or

𝟎

+𝟏β

𝟎

𝟎γ

α

alpha

β-

Beta

β+

Positron

γ

Gamma

Rays

-1

+1

0

4

0 (very

little)

0 (very

little)

0 (light

energy)

low

moderate

moderate

high

• Penetration Strength= How far into a material the radioactive

particle will go

o The _________ the particle (less mass), the more it can penetrate

o The more a particle can penetrate, the ________________it is

What is the most dangerous particle?

smaller

more dangerous

gamma rays

IV. Types of Transmutations

• Transmutation = when a ________ decays and _______ into a new and

different nucleus (aka radioactive decay)

1. Natural Transmutation= when an ________ nucleus _______________

breaks up and releases particles and/or energy in order to become more

stable

o Table ___ is a list of isotopes that undergo natural transmutation

Shows what type of particles they release (aka decay mode) and

their half-lives (how long it takes to decay)

nucleus changes

unstable spontaneously

N

Check for Understanding

Table N contains a list of some of the more common radioisotopes, their half-lives, their symbols, and their names. NUCLIDE = an ISOTOPE of a given element

1. Which of the following pairs of nuclides has the same type of radioactive decay mode?

a. K-37 and K-42

b. Fr-220 and Th-232

c. Ne-19 and P-32

d. U-232 and U-235

2. Which of the following radioisotopes will take the longest to decay from 100 g to 50 g?

a. Fe-53

b. Pu-239

c. Th-232

d. N-16

3. Which of the radioisotopes listed

below emits a decay product with a

positive charge?

a. Ra-226

b. Au-198

c. H-3

d. Sr-90

4. Which of the radioisotopes listed

below emits a decay product with the

greatest mass?

a. Co-60

b. C-14

c. Ca-37

d. Fr-220

2. Artificial Transmutation= when a ______ nucleus

gets _____________ or hit by another particle,

producing new elements

o “__________” reaction– doesn’t happen naturally

stable

bombarded

man-made

V. Nuclear Equations

Summary of Types of Reactions

A. Physical Reaction: H2O (s) H2O (l)

Same? Different?

B. Chemical Reaction: 2H2(g) + O2(g) 2H2O (l)

Same? Different?

C. Nuclear Reaction: 167N 0

-1e + 168O

Same? Different?

Compound and mass (and

charge) Phases (s l)

Mass and # of atoms (and

charge)compounds

Mass and charge elements

• As mentioned before, there are two types of decay: natural and artificial

1. Natural Decay - because the process is spontaneous, natural

radioactivity equations always have _____________forming

_______________

o Use Table ___ to identify the type of decay for specific nuclide

o Use Table ___ to identify notation of decay mode

Examples:

1. Francium – 220

2. Gold – 198

3. Neon – 19

two productsone reactant

N

O

4. Iodine– 131

5. Uranium– 233

6. Potassium – 37

How do you balance nuclear equations?

Sum of charges and mass numbers are equal on

both sides

2. Artificial Decay - because artificial transmutation involves a stable

nucleus being “forced” to change, the equation always involves

______________ forming new products

Examples:

1. 94 Be + _____ 126 C + 10 n

2. 2713Al + 42 He 1

0 n + _____

42 He

3015 P

Natural Decay Common to Both Artificial Decay

• ________ nucleus

decays by itself

(___________)

• __ reactant

• Produces

______________

• Mass and charge

conserved

• Both form new

elements

• Both produce

energy

• _______ nucleus

has to get hit to

decay

• __ reactants

• Produces

_______________

two reactants

Unstable

spontaneous

Stable

more energy

1 2

less energy

Check for Understanding

1. Given the reaction:

Which particle is represented by X?

1.

2.

3.

4.

2. Which equation represents a spontaneous transmutation?

1. Ca(s) + 2H2O(ℓ) → Ca(OH)2(aq) + H2(g)

2. 2KClO3(s) → 2KCl(s) + 3O2(g)

3.

4.

VI. Fission and Fusion

• Fission = ________ of a ______ nucleus ____________ nuclei

o ________ neutrons and large amount of ________

o _____________ and _______________ are most commonly used

Example: Fission of Uranium-235 (ANIMATION)

23592U + 10n 92

36Kr + 14156Ba + 3 10n + ENERGY

splitting large into smaller

energy

Uranium-235 plutonium-239

releases

• Fusion = ____________________________nuclei

__________________ one (greater mass)

o Creates _______________________

o ____________ is most commonly used in fusion reactions

Example: Fusion of Hydrogen nuclei

31H + 21H 4

2He + 10n + ENERGY

combining (or fusing) of smaller

to produce a larger

more energy than fission

Hydrogen-1

Nuclear Fission Common to Both Nuclear Fusion

• ___________

nucleus

_____________

particles

• Used to produce

________________

_______

• Produces

_______________

• __________ two

_______ nuclei

together to _______

a _______ one

• Used by _______!

• Produces essentially

_________________

• Both generate

energy the same way

(Convert _____

_______)

____________

___________

electricity in power

plants

radioactive waste

massenergy

Less energy

more energy

the sun

no radioactive waste

Splits larger

into smaller

combines

small form

larger

VII. Half-Life

• Half-Life = ______ it takes for ______ of the original sample of

radioactive nuclei __________

o During one half-life, half of the radioactive nuclei break down and

change into ______________________

o With each additional half-life, the sample keeps “cutting” in half, but

_______________________- all the radioactive nuclei never fully

change into stable nuclei

• The shorter the half-life, the less time an unstable isotope is emitting

radiation before it decays into something more stable and less

dangerous

• The half-life of many radioactive isotopes can be found on Table_____

Equation: 𝑡𝑜𝑡𝑎𝑙 𝑡𝑖𝑚𝑒 𝑝𝑎𝑠𝑠𝑒𝑑

ℎ𝑎𝑙𝑓 𝑙𝑖𝑓𝑒= # of half-lives

N

time half

to decay

new, more stable nuclei

never fully reaches zero

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Examples:

1. 131I is a radioactive substance used to detect and treat thyroid cancer.

What mass of I-131 remains 24 days after a 2 microgram sample is

administered to a patient?

2. Radon-222 is a carcinogenic house pollutant. How much time must

elapse before 20 grams of radon-222 decays, leaving only 1.25

grams of the original isotope?

3. Based on Reference Table N, what fraction of a radioactive 42K

sample would remain unchanged after 24.7 hours?

4. Based on the graph below, what is the half-life of this substance?

5. What fraction of a sample of cobalt-60 remains radioactive after

3 half-lives?

Uses/benefits

• Dating: Certain radioisotopes with ______________ can be used

to trace the age of substances using their half-life

Examples:

o _______________ can be used to trace the

____________________ (people, plants, animals) because all

living things contain carbon

o ________ can be used to trace the _____________ since

uranium is a natural part of some rocks and has an extremely

long half-life

• Medical: Certain radioisotopes with _______________ can be used

for medical reasons – shorter half-life means they quickly decay into

something stable before they cause harm to the body

Examples:

o Iodine – 131 – used to detect and treat thyroid cancer

o Cobalt – 60 – emits gamma rays that can destroy cancer

o Technetium 99 – detects cancerous tumors

VIII. Uses and Dangers of Nuclear Chemistry

longer half-lives

Carbon – 14 (C-14)

age of any living thing

Uranium age of the Earth

shorter half-lives

Dangers/Risks

• Large amounts of radiation given

off by isotopes can cause

environmental damage and serious

illnesses

• The isotopes used in nuclear power

plants produce waste products that

have _____________ so they

remain radioactive for long periods

of time, making them

___________________________

o accidents can also release

harmful radioactive waste into

air and water

Chernobyl, Ukraine

(1986) (news report)long half-lives

difficult to store and dispose of