Electric field

C.12ABC: Nuclear Chemistry Atomic Structure and Nuclear Chemistry RADIATION REFERENCE Alpha Radiation An alpha particle is a helium nucleus without a...
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C.12ABC: Nuclear Chemistry Atomic Structure and Nuclear Chemistry

RADIATION REFERENCE Alpha Radiation An alpha particle is a helium nucleus without any electrons. Since the helium atom has 2 protons and 2 neutrons in its nucleus, an alpha particle has a positive charge of +2. 4 2

Mass number Atomic number

α

4 2 He

or

When alpha particles are emitted from a radioactive source and an electric field is applied, the radiation beam is deflected towards the negative plate because of the attraction of the positive alpha particles to the negative side of the electric field. Alpha particles are the largest type of radiation particle and the most highly charged. They can be blocked by your hand, your clothes, or a sheet of paper.

Electric field

+ + + + + + + Paper

source

- - - - - - -

Below is an example of an alpha particle emission by radioactive Radium-224. Note that the mass number and atomic number must be conserved in the nuclear equation. 224

88 Ra

à

4

2 He

+

220

86

Mass number 224 = 4 + 220 Atomic number 88 = 2 + 86

Rn

This is the balanced nuclear reaction of the radioactive decay of Radium-224 to Radon-220.

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C.12ABC: Nuclear Chemistry Atomic Structure and Nuclear Chemistry

RADIATION REFERENCE Beta Radiation A beta particle is an electron that is emitted due to the radioactive decay of a nucleus. When there is an uneven ratio of neutrons to protons in the nucleus, an excess neutron will split. This results in a proton, which stays in the nucleus, and an electron, which is emitted as a beta particle. Beta particles have a mass of zero and a charge of -1. 0 -1

Mass number Atomic number



β

or

0 -1 e

When beta particles are emitted from a radioactive source and an electric field is applied, the radiation beam is deflected towards the positive plate because of the attraction of the negative beta particles to the positive side of the electric field. Beta particles are fast-moving and can have high energy. They can be blocked by a piece of thin metal foil. Electric field

+ + + + + + + source

Paper

Metal foil

- - - - - - -

Below is an example of a beta particle emission by radioactive Lead-210. Note that the mass number and atomic number must be conserved in the nuclear equation. 210

82 Pb

à

0

-1 e

+

210

83

Mass number 210 = 0 + 210 Atomic number 82 = -1 + 83

Bi

This is the balanced nuclear reaction of the radioactive decay of Lead-210 to Bismuth-210.

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C.12ABC: Nuclear Chemistry Atomic Structure and Nuclear Chemistry

RADIATION REFERENCE Gamma Radiation Gamma radiation is made up of high-energy photons or rays. Gamma rays have no mass and no charge and are usually emitted along with alpha and beta decay as a way for the nucleus to get rid of excess energy and achieve stability during a nuclear reaction. Mass number Atomic number

0 0 When gamma rays are emitted from a radioactive source and an electric field is applied, the radiation beam is not deflected towards the positive or negative plate because gamma rays are not charged.

γ

Electric field

source

+ + + + + + + Paper

- - - - - - -

Foil

Concrete Concret e

High frequency gamma rays are the most penetrating type of radiation and the most harmful to humans because they can cause tissue and cell damage. The high-energy photons can go through paper and metal foil and can only be stopped by a thick lead shield or a concrete block.

When a radioactive element undergoes radioactive decay and emits particle radiation, gamma rays are frequently emitted as well. The nuclear reaction can be represented by a nuclear equation in which only the nuclei of the elements are present. Gamma rays are not usually included since they do not change the mass or charge of the products in the reaction, but can be written to demonstrate the change from an excited state to a more stable, ground state. 60 27 Co

à

60 28

0

0

Ni + -1e + 2 0 γ

Cobalt-60 decays by beta emission to excited Nickel-60. Then the excited 60Ni falls to the stable ground state of 60Ni by the emission of two gamma rays.

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C.12ABC: Nuclear Chemistry Atomic Structure and Nuclear Chemistry

ISOTOPE REFERENCE Isotope 1 The element phosphorus in found in many organic molecules. Adenosine triphosphate or ATP is your body’s main form of energy. Phosphorus also helps maintain cell structure in the form of phospholipids, keeping cells separate but permeable to compounds in your bloodstream. Phosphorus-32 is a radioactive isotope of phosphorus that doctors use to examine and map metabolic pathways in the human body. Cells that are multiplying abnormally accumulate more phosphorus than normal cells. Injecting phosphorus-32 into the body allows doctors to find cancerous tumors by using the radioactivity emitted from Phosphorus-32 as a tracer to pinpoint the location of the tumors. A common way to produce radioactive isotopes is to put a stable isotope in a nuclear reactor and create a nuclear reaction that produces neutrons. The neutrons bombard everything in the reactor, including the stable isotope, and it absorbs the neutrons into its nucleus. Radioactive Phosphorus-32 is produced in a small-scale nuclear reactor by bombarding Sulfur-32 isotopes with neutrons to make Sulfur-33. Unstable radioactive Sulfur-33 emits a proton to make Phosphorus-32. 33

16 S

à

1 1H

+

32 15

P

Radioactive Phosphorus-32 is also unstable, and half of the amount that is produced is gone after 14.5 days. Most radioactive isotopes that are used in nuclear medicine are selected because they do not last very long. Their half-life, or the amount of time it takes for ½ of the amount of the isotope to decay is short. The radioactive isotope soon forms a more stable element that is not harmful to body tissues. Phosphorus-32 undergoes beta decay to form Sulfur-32. Phosphorus-32à beta decayà Sulfur-32 Some radioactive isotopes used in nuclear medicine are administered, and the radioactivity emitted internally is monitored and used to construct an image of a specific area of the body’s tissues. This is different from the way radioactivity is used in diagnostic x-rays, externally passing the rays through the body to produce an image of the denser parts of the body.

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C.12ABC: Nuclear Chemistry Atomic Structure and Nuclear Chemistry

ISOTOPE REFERENCE Isotope 2 The element iodine is found in the human thyroid, an endocrine gland which controls the body’s metabolism and regulates other systems in your body. When iodine is ingested, most of it accumulates in the thyroid gland. Iodine-131 is a radioactive isotope of iodine that doctors use to treat diseases associated with this gland. Grave’s disease, an illness caused by an overactive thyroid, is easily treated by Iodine-131. The radioactive iodine is injected and over time destroys the overactive thyroid gland, and the patient relies on synthetic hormones to replace what the thyroid gland was producing. A common way to produce radioactive isotopes is to put a stable isotope in a nuclear reactor and create a nuclear reaction that produces neutrons. The neutrons bombard everything in the reactor, including the stable isotope, and it absorbs the neutrons into its nucleus. Radioactive Iodine-131 is produced in a small-scale nuclear reactor by bombarding Tellurium-130 with neutrons to make Tellurium-131. Unstable radioactive Tellurium-131 undergoes beta decay to make Iodine-131. 131 52 Te

à

0 -1

β

+

131 53

I

Radioactive Iodine-131 is also unstable, and half of the amount that is produced is gone after 8 days. Most radioactive isotopes that are used in nuclear medicine are selected because they do not last very long. Their half-life, or the amount of time it takes for ½ of the amount of the isotope to decay is short. The radioactive isotope soon forms a more stable element that is not harmful to body tissues. Iodine-131 undergoes beta decay to form Xenon-131. Iodine-131 à beta decay à Xenon-131 Some radioactive isotopes used in nuclear medicine are administered, and the radioactivity emitted internally is monitored and used to destroy cells in a specific location in the body. This is different from the way radioactivity is used in diagnostic x-rays, externally passing the rays through the body to produce an image of the denser parts of the body. It is also safer because smaller amounts of radiation are used, and the internal radioactive isotopes decay to a less harmful form.

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C.12ABC: Nuclear Chemistry Atomic Structure and Nuclear Chemistry

ISOTOPE REFERENCE Isotope 3 Radioactive iridium is used to treat cancer of the head and breast by implanting small wires made of Iridium-192 into the affected area. The radiation, in the form of gamma rays, emitted over time from the radioactive source destroys the cancer cells surrounding it. This specialized form of cancer treatment is called brachytherapy and is characterized by the use of implanted sources of radiation designed to affect a small area of the body. A common way to produce radioactive isotopes is to put a stable isotope in a nuclear reactor and create a nuclear reaction that produces neutrons. The neutrons bombard everything in the reactor, including the stable isotope, and the it absorbs the neutrons into its nucleus. Radioactive Iridium-192 is produced in a small-scale nuclear reactor by bombarding naturally occurring Iridium-191 with neutrons to make Iridium-192. Iridium-191 absorbs a neutron to become radioactive Iridium-192.

191 77 Ir

+

1 0n

à

192 77

Ir

Radioactive Iridium-192 is unstable, and half of the amount that is produced is gone after 74 days. Most radioactive isotopes that are used in nuclear medicine are selected because they do not last very long. Their half-life, or the amount of time it takes for ½ of the amount of the isotope to decay is short. The radioactive isotope soon forms a more stable element that is not harmful to body tissues. Iridium-192 undergoes beta decay to form Platinum-192. Iridium-192 à beta decay à Platinum-192 Some radioactive isotopes used in nuclear medicine are administered, and the radioactivity emitted internally is monitored and used to target and destroy cells in a specific area of the body. This is different from the way radioactivity is used in diagnostic x-rays, externally passing the rays through the body to produce an image of the denser parts of the body. It is also safer because smaller amounts of radiation are used, and the internal radioactive isotopes decay to a less harmful form.

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C.12ABC: Nuclear Chemistry Atomic Structure and Nuclear Chemistry

ISOTOPE REFERENCE Isotope 4 Gadolinium is an inner transition metal with slight magnetic properties. It is used in magnetic resonance imaging (MRI) to enhance the contrast in medical images of the body and produce a clearer picture. The gamma rays produced by radioactive gadolinium-153 are also used to detect mineral density in the hip and back bones, making it useful in the diagnosis of osteoporosis. A common way to produce radioactive isotopes is to put a stable isotope in a nuclear reactor and create a nuclear reaction that produces neutrons. The neutrons bombard everything in the reactor, including the stable isotope, and it absorbs the neutrons into its nucleus. Radioactive Gadolinium-153 is produced in a small-scale nuclear reactor when neutron enriched Europium-153 undergoes beta decay. 153 63 Eu

à

0 -1

β

+

153 64

Gd

Radioactive Gadolinium-153 is unstable, and half of the amount that is produced is gone after 240 days. The half-life of a radioactive isotope is the amount of time it takes for ½ of the amount of the isotope to decay. Gadolinium-153 undergoes beta decay to form Terbium-153, a more stable element. Gadolinium-153 à beta decay à Terbium-153 Some radioactive isotopes used in nuclear medicine are administered, and the radioactivity emitted internally is monitored and used to construct an image of a specific area of the body’s tissues. This is different from the way radioactivity is used in diagnostic x-rays, externally passing the rays through the body to produce an image of the denser parts of the body. It is also safer because smaller amounts of radiation are used, and the internal radioactive isotopes decay to a less harmful form.

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