Nuclear Chemistry
Isotopes
Isotopes
• Nucleon: Protons and Neutrons
• The nucleons are bound together by
a strong force.
• Isotopes: atoms of a given element
with:
same #protons
but
different # neutrons
Radioactive Isotopes
• Isotopes of certain
unstable elements that
spontaneously emit
particles and energy
from the nucleus.
Radioactive Isotopes
• Half–life: The time required to convert one
half of a reactant to product. The term is
commonly applied to radioactive decay.
– The shorter the half-life, the more unstable the
isotope is!!!!
Radioactive Isotopes
Marie Curie
• 1898 discovered the
elements polonium
and radium.
• Winner of 1903 Nobel Prize for Physics with Henri Becquerel and her husband, Pierre Curie.
• Winner of the sole 1911 Nobel Prize for Chemistry.
http://www.time.com/time/specials/packages/article/0,288
04,1916052_1916054_1916019,00.html
Alpha Decay
alpha particles (𝟒𝟐𝐇𝐞;
𝟒𝟐
a ; a) :
• Emitted helium nuclei
• two protons and two neutrons
• charge +2
• can travel a few inches
through air
• can be stopped by a sheet of
paper, clothing.
Alpha Decay
http://education.jlab.org/glossary/alphadecay.gif
Beta Decay
• Beta particles (𝟎−𝟏
e;𝟎−𝟏
b; b–):
electrons ejected from the nucleus when neutrons decay
n p+ + b-
• Beta particles have the same charge and mass as "normal" electrons.
• Can be stopped by aluminum foil or a block of wood.
Beta Decay
http://www.hk-phy.org/energy/power/nuclear_phy02_e.html
Gamma Decay
• Gamma radiation (g; 𝟎𝟎𝛾):
electromagnetic energy that is
released.
• Gamma rays are electromagnetic
waves.
• They have no mass and no charge.
• Most penetrating, can be stopped by
1m thick concrete or a several cm
thick sheet of lead.
Gamma Decay
http://www.odec.ca/projects/2007/pete7o2/Background.html
Nuclear Fission
• large nuclei break apart into two or
more stable elements
• Used in nuclear power plants
primarily by the fission of uranium
• Used in the atom bomb
• Driven by chain reactions.
Nuclear Fission
http://www.sciencebuzz.org/buzz_tags/nuclear_fission
Chain Reactions
http://www.tutorvista.com/content/physics/physics-iv/atoms-and-nuclei/nuclear-fission.php
Where the
particle
that starts
a nuclear
reaction is
also one
of the
products
Nuclear Fusion
• Small nuclei combine2H + 3H 4He + 1n +1 1 2 0
• Occurs in the sun and other stars
• Used in the hydrogen bomb.
• Excessive heat can not be contained
• Attempts at “cold” fusion have
FAILED.
Energy
Nuclear Fusion
http://knol.google.com/k/nuclear-energy-and-nuclear-power-plants
Balancing Nuclear Reactions
•In the reactants (starting materials –
on the left side of an equation) and
products (final products – on the right
side of an equation)
Atomic numbers must balance
and
Mass numbers must balance
•Use a particle or isotope to fill in the
missing protons and neutrons
Balancing Nuclear Reactions
• Alpha emissions:
• Note that mass number (A) goes
down by 4 and atomic number (Z)
goes down by 2
HINT HINT: This is the atomic number
and mass number of helium (He)
Balancing Nuclear Reactions
• Beta emission:
• Note that mass number (A) is
unchanged and atomic number (Z)
goes up by 1.
HINT HINT: this is a release of an
electron and a gain of a proton.