Absolute Age Flashcards
What is absolute age used for?
To determine the actual (numerical) age of the rock
What is used to find the absolute age of something?
Certain elements that experience radioactive decay
Radioactive decay:
The spontaneous and natural breakdown from unstable to stable atomic forms
What happens during the radioactive decay process?
Energy is released
Describe the radioactive decay process.
The process has a constant and predictable rate unaffected by the environmental changes
Radioactive isotope:
The unstable form of an element which has a different number of neutrons in their atomic nucei
Decay product:
When a radioactive isotope breaks down to a stable form, it creates what is known as a decay product
Half-life:
The time it takes a radioactive isotope to decay to half of its original amount
Half-life occurs at a ___ rate:
Predictable
Radioactive isotopes: Carbon-14:
- Decays into N-14
- Used to date once living things
- Can be used to date things as old as 54,000 years
- After 54,000 years there isn’t enough C-14 left to accurately date the object
Radioactive isotope: Potassium-40:
- K-40 decays into stable Ar-40 & Ca-40
- Used for rocks & fossils
- Used for old objects-> 1,300,000,000
Radioactive isotope: Uranium-238:
- U-238 decays into stable Pb-206
- Used to date very old rock and very old fossils up to and over 4,600,000,000
Radioactive isotope: Rubidium-87:
- Rb-87 decays in to Strontium-87
- Used to date extremely old rock and extremely old fossils
