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.