NUCLEAR
CHEMISTRY
An Energetic Concept
WHO DID WHAT
 Wilhelm
Roentgen
 Laboratory generated
phosphorescence
 X-rays
WHO DID WHAT
 Henri
Becquerel
 Inherited U salts (pitchblende)
 Natural phosphorescence
 Discovered spontaneous
phosphorescence
WHO DID WHAT
 Marie
& Pierre Curie
 Studied Becquerel
phosphorescence and named it
 Discovered Po, Ra
ISOTOPE REVIEW
A
X
Z
A—mass number
Z—atomic number
A – Z = number of neutrons
SO, WHAT IS RADIATION?
 Instability
due to n:p+
 Radioisotopes
 Goal is stability
SO, WHAT IS RADIATION?
TYPES OF RADIATION
 Rutherford
 Electric
field effect on radioactivity
Alpha
Beta
Gamma

TYPES OF RADIATION
TYPES OF RADIATION
 Alpha
()
 Same as a He-4 nucleus
 A decreases by 4
 Z decreases by 2
TYPES OF RADIATION
 Alpha
 Not
very penetrating
Stopped by a sheet of paper
 Very ionizing
TYPES OF RADIATION
 Beta
()
 Same as an electron
 A remains the same
 Z increases by 1
e
TYPES OF RADIATION
 Beta
penetrating than 
Stopped by a thin sheet of metal
 Less ionizing than 
 More
TYPES OF RADIATION
 Gamma
()
 Pure energy
 Usually accompanies and 
 More penetrating than and 
Somewhat blocked by several
inches of Pb or several feet of
concrete
 Less ionizing than and 
TYPES OF RADIATION
 Positron
(+)
 Same mass as 
 Opposite charge of 
18
9
F O+ e
18
0
8
+1
TYPES OF RADIATION
 Electron
capture
 The opposite of  emission
 A remains the same
 Z decreases by 1
40
19
K+
0
-1
40
e  Ar
18
DECAY SERIES
 Continued
radiation until stable
 Fr-221 undergoes the following
decay series: ,,,,,
221
87
217
85
213
83
209
81
209
82
Fr 
217
85
At 
213
83
Bi 
209
81
Tl 
209
82
Pb 
209
83
209
83
Bi 
At +
4
2
He
Bi +
4
2
He
Tl +
4
2
He
Pb +
0
-1
e
Bi +
0
-1
e
Tl +
4
2
205
81
He
RATE OF RADIOACTIVE
DECAY
 Half-Life
 t½
= 0.693/k
k = rate law constant
 First-order Kinetics
 lnN = –kt + lnNo
N…amount after elapsed time
t = elapsed time
No = amount originally
UNITS OF RADIOACTIVE
DECAY
 curie
(Ci)
10 disintegrations
1 Ci = 3.7 x 10
per second
~activity of 1 g of Ra-226
 becquerel (Bq)
SI unit
1 Bq = 1 dis/s…37 GBq = 1 Ci
UNITS OF RADIATION
EXPOSURE
 sievert
(Sv)
 Dose absorbed by specific tissue
 Replaced röntgen equivalent to
man (rem)
 1 Sv…nausea
 2-5 Sv…hair loss, hemorrhage
 3 Sv…death in 50% of people in 30
days
 >6 Sv…unlikely survival
 Typical background exposure is
2.4 mSv/year
RATE OF RADIOACTIVE
DECAY
 The
half-life of F-18 is 2 hours. If
you receive a dose of 200 mCi at 8:00
AM, how long will it take for 10 mCi
to remain in your body? At what
time will you have 10 mCi in you?
 Solve for the value of k
 Plug into the linear equation and
solve for t
RATE OF RADIOACTIVE
DECAY
2 h = 0.693/k…
k = 0.3465 h-1
ln(10 mCi) = –(0.3465 h-1)(t) + ln(200 mCi)
ln(10 mCi) – ln(200 mCi) = –(0.3465 h-1)(t)
– 2.996= –(0.3465 h-1)(t)
8.65 h = t
at 4:39 PM, you will have 10 mCi in you
RADIOACTIVE DATING
 C-14
is a beta emitter with a half-life
of 5730 years
 Used to determine the age of carbonbased substances