Radioactive Decay and Half-Life in Nuclear Chemistry
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Section 3: Radioactive Decay and
Half-Life
The
spontaneous
emission of rays or
particles from certain nuclei as they
“decay,” such as
Uranium
.
These rays or particles are called
nuclear
radiation
.
They come in three types:
Alpha Radiation:
Helium nucleus
; 2
+
Charge;
Low
power (0.05 mm body tissue)
Beta Radiation:
electron
; 1
-
Charge;
Moderate
power (4 mm body tissue)
Gamma Radiation:
electromagnetic wave
; neutral
charge;
High
Power (penetrates entire body easily)
While the process is
spontaneous
, it is not
instantaneous
… it takes
time!
The time required for HALF
of the atoms of a radioactive
substance to decay is called
a
half-life
.
Fluorine 18 ( F) has a
half-life of 110 seconds.
This material is used
extensively in medicine.
The hospital laboratory
begins the day with 10
grams of F…
18
9
18
9
1 half-life = 110 seconds
660 seconds
110 seconds
= 6 half-lives
6 half-lives = 10 divided in half, 6 times
1)
10/2 = 5 grams
2)
5/2 = 2.5 grams
3)
2.5/2 = 1.25 grams
4)
1.25/2 = 0.625 grams
5)
0.625/2 = 0.3125 grams
6)
0.3125/2 = 0.15625 grams
After 11 minutes, only 0.16 g of
the 10 g sample remain!!!!!!
Exploring the concept of radioactive decay and half-life in nuclear chemistry, this content covers the types of nuclear radiation, alpha decay of Uranium, and the significance of half-life in determining the decay of radioactive substances such as Carbon-14. An example with Fluorine-18 illustrates the calculation of remaining material after a specific time, highlighting the practical application of these concepts.
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Presentation Transcript
UNIT 14: NUCLEAR CHEMISTRY Section 3: Radioactive Decay and Half-Life
RADIOACTIVE DECAY The spontaneous emission of rays or particles from certain nuclei as they decay, such as Uranium. These rays or particles are called nuclear radiation. They come in three types: Alpha Radiation: Helium nucleus; 2+Charge; Low power (0.05 mm body tissue) Beta Radiation: electron; 1-Charge; Moderate power (4 mm body tissue) Gamma Radiation: electromagnetic wave; neutral charge; High Power (penetrates entire body easily)
HALF-LIFE While the process is spontaneous, it is not instantaneous it takes time! The time required for HALF of the atoms of a radioactive substance to decay is called a half-life.
EXAMPLE: FLUORINE-18 18 Fluorine 18 ( F) has a half-life of 110 seconds. This material is used extensively in medicine. The hospital laboratory begins the day with 10 grams of F 9 9 18
HOW MANY HALF-LIVES OF F-18 OCCUR IN 11 MINUTES (660 SEC)? 1 half-life = 110 seconds 660 seconds 110 seconds= 6 half-lives
HOW MUCH OF THE 10-GRAM SAMPLE WOULD BE LEFT AFTER 11 MINUTES? 6 half-lives = 10 divided in half, 6 times 1) 10/2 = 5 grams 2) 5/2 = 2.5 grams 3) 2.5/2 = 1.25 grams 4) 1.25/2 = 0.625 grams 5) 0.625/2 = 0.3125 grams 6) 0.3125/2 = 0.15625 grams After 11 minutes, only 0.16 g of the 10 g sample remain!!!!!!
