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Name: _______________________________________Period: ____________

Unit 15: Nuclear Chemistry Guided Notes

Introduction to Nuclear Chemistry

Nuclear chemistry is the study of the structure of ___________________________________________and the ___________________________ they undergo.

Characteristics of nuclear reactions:

Isotopes of one element are changed into isotopes of another _____________________________

Contents of the __________________________ change

Large amounts of _________________________ are released

Chemical Reactions

Nuclear Reactions

__________________________ are broken

______________________ emit particles and/or rays

Atoms are rearranged

Atoms change into atoms of a different _________________________________

Involves ____________________________ electrons

Involves __________________, _________________, and/or _______________________

______________________________ energy changes

______________________________ energy changes

____________________________________ process by which atoms give off rays or particles

____________________________________ the penetrating rays and particles emitted by a radioactive source

The Discovery of Radioactivity (__________-___________)

Roentgen found that invisible rays were emitted when electrons hit the surface of a fluorescent screen (discovered ________________________)

Becquerel accidently discovered that phosphorescent __________________________ rock produced spots on photographic plates (discovered ___________________________________)

Marie and Pierre Currie:

isolated the components emitting the rays (uranium atoms)

identified 2 new elements, _____________________ and _____________________ on the basis of their radioactivity

These findings contradicted _______________________________ theory of indivisible atoms.

Review of Atomic Structure

Nucleus

Electron Cloud

Majority of the __________________________ of the atom (99.9%)

None of the _____________________________ of the atom (0.01%)

None of the _____________________________ of the atom (0.01%)

Majority of the __________________________ of the atom (_____________________ times the size of the nucleus)

______________ (p+) and ______________ (n0)

______________(e-)

______________________ charged

______________________ charged

__________________________________ force holds the protons together

Weak _____________________________ force between negatively charged electrons and positively charged nucleus

___________________________ particles found in the nucleus of an atom

neutrons and protons

The nuclear symbol consists of three parts:

Element symbol

Atomic number (Z) number of _________________________ in the nucleus

_____________________ number (A) sum of the number of protons and neutrons

Also written as the element name dash (-) mass number (example: ____________________________________)

_____________________________ each unique atom

Ion- an atom with a _______________________________

Radioactivity

Isotopes atoms of the same element with different numbers of _________________________________

Radioisotopes isotopes of atoms with ___________________________ nuclei (too many or too few neutrons)

Radioactive decay when unstable nuclei lose energy by emitting ___________________________________ to become more stable

This is a spontaneous reaction (happens on its own)

Nuclear Stability

Elements with atomic #s ______ to ______ are very stable.

Isotope is completely stable if the nucleus will not spontaneously __________________________.

______:______ ratio of protons:neutrons (p+; n0)

Example: Carbon 12 has ______ protons and ______ neutrons

Elements with atomic #s ______ to ______ are marginally stable.

______:______ ratio of protons:neutrons (p+:n0)

Example: Mercury 200 has ______ protons and ______ neutrons

Elements with atomic #s _________________ are unstable and radioactive.

Examples: Uranium and Plutonium

Nuclear Reactions

Types of Nuclear Reactions:

___________________________________________ alpha and beta particles and gamma ray emission

Nuclear ___________________________________________________ - emission of a proton or neutron

Transmutation the conversion of an atom of one element to an atom of a different _______________________.

Usually occurs by radioactive decay

Nuclear equation shows the radioactive decomposition of an element

Alpha Radiation

Composition Alpha particles, same as a __________________________________ nuclei

Symbol Helium nuclei, ________________,

Charge ________________

Deflected towards a _________________________________ charged plate

Mass ______ amu

Approximate energy 5.0 MeV

Penetrating power ________________ (0.05 mm body tissue)

Shielding _______________________________________________________________

Alpha Decay Equations

Step 1: Write the element that you are starting with followed by the yields symbol.

Step 2: Write the alpha particle as a product

Step 3: Determine the other product using atomic #.

Step 4: Determine mass and ensure everything is balanced.

(Net effect is loss of __________ in mass number and loss of ___________ in atomic number.)

Example 1: Write the nuclear equation for the radioactive decay of polonium 210 by alpha emission. ___________________________________________________________________________________________

Example 2: Write the nuclear equation for the radioactive decay of radium 226 by alpha emission. ___________________________________________________________________________________________

Beta Radiation

Composition Beta particles, same as a fast moving __________________________________

A neutron is converted to a ______________________ an a _________________________ particle

Symbol e--, ________________

Charge ________________

Deflected towards a _________________________________ charged plate

Mass ______ amu

Approximate energy 0.05 1 MeV

Penetrating power ________________ (4 mm body tissue)

Shielding _______________________________________________________________

Beta Decay Equations

Same steps as alpha equations except use a beta particle

(Net effect is ______________ change in mass and an addition of ______ in atomic number.)

Example 3: Write the nuclear equation for the radioactive decay of carbon 14 by beta emission. ___________________________________________________________________________________________

Example 4: Write the nuclear equation for the radioactive decay of zirconium 97 by beta decay. ___________________________________________________________________________________________

Gamma Radiation

Composition gamma, High-energy electromagnetic radiation or high energy ____________________________

Usually accompanied by ______________________ and _________________________ radiation

Symbol ______________________________

Charge ________________

Mass ______ amu

Approximate energy 1 MeV

Penetrating power ________________ (penetrates body easily)

Shielding _______________________________________________________________

Beta Decay Equations

Steps: include alpha and/or beta, and gamma decay

Example 5: Write the nuclear equation for the radioactive decay of uranium 238 by gamma decay accompanied with alpha decay. _________________________________________________________________

Type of Radioactive Decay

Particle Emitted

Change in Mass #

Change in Atomic #

Alpha

Beta

Gamma

______________________________________________: when a substance undergoes a series of nuclear decay

Half-Life

Half-life is the ______________________ required for ____________________ of a radioisotopes nuclei to decay into its products.

For any radioisotope,

# of lives

% Remaining

100%

50%

25%

12.5%

6.25%

3.125%

1.5625%

Example 6: suppose you have 10.0 grams of strontium 90, which has a half-life of 29 years. How much will be remaining after x number of years?

You can use a table:

# of lives

Time (years)

Amount Remaining (g)

0

1

2

3

4

OR you can use an equation

Example 7: If gallium 68 has a half-life of 68.3 minutes, how much of a 160.0 mg sample is left after 1 half life? ________ 2 half lives? __________ 3 half lives? __________

Example 8: Cobalt 60, with a half-life of 5 years, is used in cancer radiation treatments. If a hospital purchases a supply of 30.0 g, how much would be left after 15 years? __________________________

Example 9: Iron-59 is used in medicine to diagnose blood circulation disorders. The half-life of iron-59 is 44.5 days. How much of a 2.000 mg sample will remain after 133.5 days? ______________

Example 10: The half-life of polonium-218 is 3.0 minutes. If you start with 20.0 g, how long will it take before only 1.25 g remains? ______________

Example 11: A sample initially contains 1