Nuclear Chemistry
Nuclear chemistry is the study of the changes of the ______of atoms.
- Nuclear Reactions involve changes within the nucleus where as chemical reactions involve the loss, gain or sharing of electrons.
The Nucleus
Contains ______and neutrons. They are collectively called ______.
Radioactivity
A ______nucleus holds together well. An unstable nucleus will decay or break down, releasing particles and/or energy in order to become stable.
An atom with an unstable nuclei is considered “______”.
There are several ways radioactive atoms can decay into different atoms!
Transmutation
Type of nuclear reaction that will change the number of ______and thus will create a different ______.
BasicTypes of Radioactive Decay
Particle Type Symbol What Happens? Example Penetrating Power
Alpha / or / Atomic number decreases by ____ and mass number decreases by ____ / (1)LOW: Can be blocked by paper/clothing***Beta / or / Atomic number increases by _____ but the mass number stays the same / (100) MEDIUM: can penetrate the skin; need to be protected by clothing/thin metals like aluminum
Gamma / / No change in atomic nor mass number; occurs with other types of decay / (100000) HIGH: need to be protected by thick concrete or metal like lead
*** A neutron becomes a ______and a high speed electron that is discharged from the nucleus.
Writing Balanced Nuclear Equations
The ______and mass number must be ______on both sides of the equation.
Alpha Decay of thorium-230
Beta Decay of cesium -137
You Try!
- Beta decay of zircomium-97
- Alpha decay of americium-241
- Alpha decay of uranium-238
- Complete this: 239 239
Np Pu + ______
93 94
Bombarding the Nucleus
All the transuranium elements (elements with atomic numbers higher than Uranium)have been made by bombarding the nucleus with neutrons and other atoms in accelerators
Half Life
Radioactive isotopes decay at a characteristic rate measured in ______.
A half life is the time required for ______of the amount of radioactive atoms to decay. The time ranges from ______to millions of ______.
T= elapsed time
T1/2 = half life
HOW TO’s
1. To calculate the number of half lives, divide the half life(T1/2) into the total time (T).
T/T1/2 = # of half lives
2. Equationto calculate remaining amount left over after a certain number of half lives have passed.
Amt remaining = (initial amt) (.5)n (# of half lives)
______
Examples:
- Suppose you have 20 grams of sodium-24. Its half-life is 15 hours. How much is left over after 60 hours.
- Uranium-238 has a half life of 4.46 x 109 years. How long will it take for 7/8th of the sample to decay?
You Try!
The half life of radium-222 is 38 s. How many grams of a 12.0 g sample are left after 114 s?
Nuclear Fusion
Smaller atoms are ______to form a large atom.
Occurs in the ______and ______
Generates huge amounts of ______
Nuclear Fission
Large atoms ______into smaller atoms
Generates huge amounts of ______.
Carried out in ______Could result in a chain reaction of fission like the ______
Tutorials:
NuclearReactions:
Half Life & Nuclear Reactions: