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Nuclear
Chemistry
Radioactivity
 The spontaneous decomposition of a
nucleus to form a different nucleus
accompanied by a release of energy or a
particle
OR
 The spontaneous transformation of an
unstable atomic nucleus into a stable
product while emitting radiation
The Nucleus

The atomic nucleus is made up of protons
and neutrons which are collectively called
nucleons.

Nuclide – in nuclear chemistry the atom
is referred to as the nuclide.
Nuclides
 Nuclides are represented by two ways:
1) Radium-228
(name of element followed by mass number, which is the # of
protons + neutrons)
2)
228 (mass number)
Ra (symbol)
88
(atomic number which is
the # of protons
as well as the # of electrons)
6C
14
1. 14
2. 6
Answer: 14
the mass number is…
6C
14
1. 14
2. 6
Answer: 6
the atomic number is…
14 C
6
1. 6
2. 14
3. 8
Answer: 6
has _____ protons
14
6C
1. 6
2. 14
3. 8
Answer: 8
has _______ neutrons…
209
1.
2.
3.
4.
84Po
has _ neutrons and _ protons
209 N, 84 P
84 N, 209 P
125 N, 84 P
84 N, 125 P
Answer: 125 N, 84 P
Cobalt – 60 has __neutrons and __
protons
1.
2.
3.
4.
5.
27 P, 33 N
27 P, 60 N
60 P, 27N
60 P, 33N
60 P, 60 N
Answer: 27 P, 33 N
Nuclear Reactions
 Chemical reactions involve the breaking
and forming of bonds between different
atoms.
 In a nuclear reaction the situation is
different – in a nuclear reaction changes
occur involving the number of protons,
neutrons, or electrons in a single atom.
Nuclear Reactions
 Proton is symbolized:
1p
1
 Electron is symbolized: 0 e
-1
 Neutron is symbolized:
1n
0
0β
-1
Nuclear Equations
 In nuclear equations the total of the atomic number and
the total of the mass number must be equal on both
sides of the equation.
Example:
9
4
12
1
Be
+
He

C
+
n
4
2
6
0
Mass Number: 9+4 = 13
12+1 = 13
Atomic Number: 4+2 = 6
6+0 = 6
 This is also called a transmutation reaction, because
the beryllium-9 became carbon-12.
Practice: Complete the following nuclear equations:
1. 218
Po
84

2. 253
Es
99
4
+ He
2
+
_________
256

Md
101
3. 142
Pm +

61
_________
214
Pb
82
+
________
142
Nd
60
Radiation
 Radiation comes from the nucleus of an atom.
 Unstable nucleus emits a particle or energy
 alpha
 beta
 gamma
A. Types of Radiation
 Alpha particle ()
 helium nucleus
 Beta particle (-)
 electron
4
2
0
-1
 Gamma ()
 high-energy photon
He
e
2+
paper
Metal
Foil
1-
0
lead
concrete
A. Types of Radiation
 Alpha particle ()
 helium nucleus
4
2
He
2+
paper
Alpha Emission – an alpha particle () is 2 protons
and 2 neutrons (or a helium atom) bound together and
is emitted from the nucleus during some kinds of
radioactive decay.
210
206
4
Po

Pb +
He
84
82
2
Paper or clothes will shield you from alpha particles.
B. Types of Radiation
 Beta particle (-)
 electron
0
-1
e
1-
Metal
Foil
Beta Emission – a beta particle () is an electron emitted
from the nucleus when a neutron is converted to a proton.
1
1

n
0
14
C
6

p
1
14
N
7
0
+

-1
0
+

-1
Metal foil will shield you from beta particles.
D. Types of Radiation
Gamma Emission – gamma rays () are high-energy
electromagnetic waves emitted from a nucleus as it
changes from an excited state to a ground energy state.
Very similar to light, but is much more dangerous.
Gamma emission usually occurs immediately following
other types of decay.
Lead or concrete will protect you from
gamma rays.
 Gamma ()
 high-energy photon
lead
0
concrete
Practice: Identify and complete the following nuclear reactions:
1.
9

__________
2. 234
Th
90

4
Be
4
234
Pa
91
+
He
2
+
___________
Practice: Identify and complete the following nuclear reactions:
3. Write an equation to represent the decay
of thorium-230 by alpha emission.
Radiation
 Effects of Radiation - The effects of
radiation depends on the amount and
exposure. Massive doses can be deadly.
 DNA molecules are sensitive to alpha,
beta, positron, gamma, and x-rays.