Transcript Radiometric Dating ppt

List the order of
events that took
place:
earthquake
deposit D
deposit B
deposit G
intrusive lava
rocky deposit R
river cuts through
deposit E
deposit A
Dating With Radioactivity
 Basic Atomic Structure
• There are protons and neutrons in an
atom’s nucleus.
• The number of neutrons in an atom can
vary - these are called isotopes.
 Radioactivity
• When nuclei are unstable, they break
apart, or decay, in a process known as
radioactivity.
• An unstable or radioactive isotope is
called a parent.
• The isotopes that result from the decay of
the parent are called daughter products.
 Half-Life
• A half-life is a common way of expressing
the rate of radioactive decay.
• A half-life is the time required for one half
of the atoms of a radioactive substance to
decay.
• HALF-LIFE GRAPH
Number of Fraction Percentage
half-lives
remaini
remainin
elapsed
ng
g
1
0
/1
100
1
1
/2
50
2
1
/4
25
3
4
5
6
7
...
n
1
/8
1
/16
1
/32
1
/64
1
/128
...
n
1/2
12
6
3
1
0
.5
.25
.125
.563
.781
...
n
100(1/2 )
Say what!?!?
 A 100g sample of Millsonite has a halflife of 5 years.
•
•
•
•
After 5 years - 50 grams remain
After 10 years - 25 grams remain
After 15 years - 12.5 grams remain
After 20 years - 6.25 grams remain
 Radiometric Dating
• Radiometric dating is the procedure of
calculating the absolute ages of rocks and
minerals that contain radioactive isotopes.
 Dating with Carbon-14
• Radiocarbon dating is the method for
determining age by comparing the amount
of Carbon-14 to the amount of Carbon-12
in a sample.
So what!
 Importance of Radiometric Dating
• Radiometric dating has been used to date
thousands of events in Earth’s history.
• Rocks on Earth have been dated to be as
much as 4 billion years old.
Classwork/Homework
PRACTICE
 Finding absolute age of a rock.
• BOOK p. 327
 Determine D/P ratio
• Practice problems