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Nuclear Radiation & Transformations

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Marie Curie

Marie Curie was a Polish scientist whose research led to many discoveries about radiation and radioactive elements. In 1934 she died from leukemia caused by her long-term exposure to radiation.

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Radioactivity

Marie Curie (1867-1934) and Pierre Curie (1859-1906) were able to show that rays emitted by uranium atoms caused fogging in photographic plates.

Marie Curie named the process by which materials give off such rays radioactivity.

The penetrating rays and particles emitted by a radioactive source are called radiation.

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Radioactivity

In nuclear reactions, the nuclei of unstable isotopes, called radioisotopes, gain stability by undergoing changes.

An unstable nucleus releases energy by emitting radiation during the process of radioactive decay.

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Types of Radiation

Alpha

Beta

Gamma

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Alpha Radiation Nuclear Symbol:

Made of:

Mass:

Charge:

2 p+ and 2 n0

4

+2

He24 α2

4or

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Alpha Decay

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Beta Radiation

An electron resulting from the breaking apart of a neutron in an atom is called a beta particle.

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Beta Radiation Nuclear Symbol:

Made of:

Mass:

Charge:

e-10 or β-1

0

electrons (-)

0

-1

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Beta Decay

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Gamma Radiation

- Usually emitted along with alpha radiation or beta radiation.

Nuclear Symbol:

Made of:

Mass:

Charge:

γ

electromagnetic waves

0

0

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Gamma-Ray Radiation

Cobalt-60

Nickel-60

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What stops alpha, beta, and gamma radiation?

Alpha particles are the least penetrating. Gamma rays are the most penetrating.

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Nuclear Stability and Decay

The stability of the nucleus determines the type of decay (alpha, beta, gamma) a radioisotope undergoes.

The protons in a nucleus want to repel against each other.

There is a strong force that holds the protons and neutrons together in the nucleus

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What makes an atom radioactive?

When the strong nuclear force cannot hold the protons and neutrons together.

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Which elements are unstable (radioactive)?

All nuclei with more than 83 protons (shade these in on the small periodic table)

However, many other nuclei with only a few protons are also radioactive

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Transmutation Reactions

The conversion of an atom of one element to an atom of another element is called transmutation.

Transmutation can occur by radioactive decay.

Transmutation can also occur when particles bombard the nucleus of an atom.

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Fission & Fusion

BOTH: release A LOT of energy

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Fission

A large nucleus is split apart.

Usually releases particles that perpetuate a chain reaction

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Fission

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Fission

A large nucleus is split apart.

Usually releases particles that perpetuate a chain reaction

Used to generate electricity and in nuclear weapons

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Fusion

2 small nuclei combine (fuse together)

Occurs at very high temperature and pressure

Occurs in the sun & other stars

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Fusion

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Geiger Counter

Used to detect radioactive substances

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Effects of Radiation

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Half-Life

HALF-LIFEHALF-LIFE is the time that it takes for 1/2 a is the time that it takes for 1/2 a sample to decay.sample to decay.

The rate of a nuclear transformation depends The rate of a nuclear transformation depends only on the “reactant” concentration.only on the “reactant” concentration.

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Half-Life

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Half-Life

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Half-Life

The ratio of Carbon-14 to stable carbon in the remains of an organism changes in a predictable way that enables the archaeologist to obtain an estimate of its age.

Radiocarbon dating is used to determine the approximate age of a sample of matter.