ACADs (08-006) Covered Keywords Radioactivity, radioactive decay, half-life, nuclide, alpha, beta, positron. Description Supporting Material

OBJECTIVES Define the following terms associated with radioactive decay: – radioactivity – radiation – radioactive decay – half-life State the difference between radioactivity and radiation. FEN-BET-I764 Rev. 02

OBJECTIVES Using the Chart of the Nuclides and given a stable nuclide, determine the following: – Element Name – Atomic Number (A) – Atomic Mass (Z) – Isotopic Mass – Atom Percent Abundance (%) FEN-BET-I764 Rev. 03

OBJECTIVES Using the Chart of the Nuclides and given a man-made radioactive nuclide, determine the following: – Element Name – Atomic Number (A) – Atomic Mass (Z) – Half-Life FEN-BET-I764 Rev. 04

OBJECTIVES Describe the following types of decay in terms of the requirements for and mode of occurrence, the resulting products, and emissions: – Alpha – Beta – Positron – Electron capture FEN-BET-I764 Rev. 05

PRESENTATION

RADIOACTIVE DECAY TERMS Radioactivity is defined as “that ability of an unstable nucleus to spontaneously emit particles and/or energy to achieve a more stable state.” Radiation is defined as “energy or particles propagated through space.” FEN-BET-I764 Rev. 07

RADIOACTIVE DECAY TERMS Radioactive decay is defined as “that process in which an unstable nucleus spontaneously emits particles and/or energy to achieve a more stable state.” Half Life (t 1/2 ), is defined as “the time required for one-half of the nuclei of a given radioactive material to undergo radioactive decay.” Half Life is unique to each nuclide and is expressed in seconds, minutes, hours, days, or years. FEN-BET-I764 Rev. 08

RADIOACTIVITY v.s. RADIATION Radioactivity The spontaneous nuclear transformation that usually results in the formation of a different nuclide. Radiation Energy or particles propagated through space. FEN-BET-I764 Rev. 09 Be sure you know the difference between these two. They are not the same!!

RADIOACTIVE DECAY As mass numbers of nuclei become larger, the neutron to proton ratio becomes larger for the stable nuclei. Non-stable nuclei may have an excess or deficiency of neutrons and undergo various decay processes such as beta (  - or  + ), alpha (  ), neutron (n), or proton (p) decay. The result of these decay processes provides a more stable configuration. FEN-BET-I764 Rev. 010

RADIOACTIVE DECAY CHART OF THE NUCLIDES

Chart of the Nuclides FEN-BET-I764 Rev. 012 The Vertical Column of Numbers lists the Atomic Number or “Z Number” for each associated row. It describes how many protons are in that row Z

Chart of the Nuclides FEN-BET-I764 Rev. 013 The Horizontal Row of Numbers lists the “N Number” for each associated column. It describes how many neutrons are in that column. N

Chart of the Nuclides FEN-BET-I764 Rev. 014 Each box in the chart contains information about that particular nuclide. Let’s look at some examples.

Chart of the Nuclides FEN-BET-I764 Rev. 015 These are the heavily bordered Squares at the end of each row. It contains the chemical symbol and properties of the element as found in nature. These properties include: H Hydrogen - Symbol - Atomic Weight (Carbon -12 Scale) - Element Name - Thermal Neutron Absorption Cross-Section in Barns Followed by Resonance Integral, in Barns  a.333,.150 Chemical Element Atomic weight Thermal neutron absorption cross-section

Stable Nuclides FEN-BET-I764 Rev. 016 Chemical symbol with atomic mass number. - Symbol, Mass Number Atom Percent Abundance - Thermal Neutron Capture Cross-Sections in Barns Leading to (Isomeric + Ground State), Followed by Resonance Integrals Leading to (Isomeric + Ground State). Isotopic Mass (Carbon - 12 Scale) - Isotopic abundance (%) Thermal neutron absorption cross section Isotopic mass of neutral atom on C12 scale A stable nuclide is naturally stable and found in nature. This box contains the following information:

Long-Lived, Naturally Occurring Radioactive Nuclides FEN-BET-I764 Rev. 017 The black rectangle indicates that the isotope is radioactive and found in nature. La e11 a Symbol, Mass Number - - Half-Life Thermal Neutron Capture Cross-Section, Followed by Resonance Integral. ,  -.25  ,  ~57,4E2 Naturally Occurring or Otherwise Available but Radioactive E Beta Disintegration Energy Followed by Isotopic Mass 5+ - Atom Percent Abundance Modes of Decay in Order of Prominence with Energy of Radiation in MeV for Alpha and Beta; keV for Gammas. Squares with both black rectangles and gray represent naturally occurring isotopes with a very long half life.

Long-Lived, Naturally Occurring Radioactive Nuclides (more) FEN-BET-I764 Rev. 018 Chemical symbol with atomic mass number. Isotopic abundance (%) Half-Life Isotopic mass of neutral atom on C12 scale La e11 a Symbol, Mass Number - - Half-Life Thermal Neutron Capture Cross-Section, Followed by Resonance Integral. ,  -.25  ,  ~57,4E2 Naturally Occuring or Otherwise Available but Radioactive E Beta Disintegration Energy Followed by Isotopic Mass 5+ - Spin and Parity - Atom Percent Abundance Modes of Decay in Order of Prominence with Energy of Radiation in MeV for Alpha and Beta; keV for Gammas. Decay modes and decay energies in MeV for ,  ; keV for .

Man-Made Radionuclides FEN-BET-I764 Rev. 019 Chemical symbol with atomic mass number. Half-Life Decay modes in MeV for ,  ; keV for . E max of Beta Energy S h - Symbol, Mass Number - Half-Life - Beta Disintegration Energy in MeV.  -.99,...  Artificially Radioactive E 2.94 Modes of Decay with Energy of Radiation in MeV for Alpha and Beta; keV for Gammas.

LINE OF STABILITY FEN-BET-I764 Rev. 020 Note that there is a line of stable atoms (gray boxes) that run diagonally through the entire Chart of the Nuclides. This is known as the “Line of Stability”. It is where all radioactive isotopes will eventually come to rest after one or more decay events.

ACADs (08-006) Covered Keywords Description Supporting Material

TYPES OF RADIOACTIVE DECAY FEN-BET-I764 Rev. 022 There are many types of Radioactive Decay. We will discuss the following: –Alpha particle emission –Beta emission (both  - and  + ); –Gamma emission –Electron capture

ALPHA EMISSION DECAY A large, loosely packed nuclei will decay by alpha emission. An alpha particle (  ) is released from its nucleus. An alpha particle (  ) is a Helium (He) nucleus (a Helium atom minus its two electrons). FEN-BET-I764 Rev. 023

ALPHA DECAY FEN-BET-I764 Rev. 024 In Alpha decay 2 neutrons and 2 protons are emitted forming an  particle. 

ALPHA EMISSION DECAY The Helium nucleus has two (2) protons, and two (2) neutrons. When released from the original nucleus, the new nucleus will have an Atomic Number two less than its original and an Atomic mass of four less than its original. Let’s look at a couple of graphic demonstrations of this type of decay on the Chart of the Nuclides. FEN-BET-I764 Rev. 025

FEN-BET-I764 Rev. 026 New Isotope Old Isotope ALPHADECAYALPHADECAY N -2 N -1 N N +1 N +2

EXAMPLE FEN-BET-I764 Rev. 027 Americium 242 emits an  and transforms into Neptunium 238

BETA MINUS DECAY In a beta minus (  - ) decay, a nuclei emits a negative charge from the nucleus. A  - is identical in charge and mass of an electron. In  - decay, a neutron is converted to a proton, causing the nuclide’s Atomic Number to increase by one (1), but the Atomic Mass to stay the same. FEN-BET-I764 Rev. 028

BETA MINUS DECAY FEN-BET-I764 Rev. 029 In Beta minus decay a neutron changes to a proton with the emission of a  -. --

BETA MINUS DECAY  - decay is the primary emission mode of radioactive nuclides that are born below the Line of Stability. Let’s look at a couple of graphic demonstrations of this type of decay on the Chart of the Nuclides. FEN-BET-I764 Rev. 030

FEN-BET-I764 Rev. 031 Old Isotope New Isotope -DECAY-DECAY N -2 N -1 N N +1 N +2

EXAMPLE OF  - DECAY FEN-BET-I764 Rev. 032 Cesium 137 emits a  - and transforms into Barium 137

POSITRON (  +) DECAY FEN-BET-I764 Rev. 033 In Positron decay, a proton changes to a neutron with the emission of a  +. ++ Besides the emission of a  +, the Atomic Number (A number) of the nucleus goes down by 1 and the Atomic Mass (Z number) stays the same.

ELECTRON CAPTURE (  ) FEN-BET-I764 Rev. 034 In Electron Capture an electron is captured by the nucleus, changing a proton to a neutron with the emission of a characteristic X-Ray and a  +. ++ X-ray The end results are the same as a  + decay discussed previously. The A number goes down by 1 and the Z number stays the same.

EXAMPLE OF  + AND  DECAY FEN-BET-I764 Rev. 035 Lanthanum 136 captures an electron or emits a  + and transforms into Barium 137

FEN-BET-I764 Rev. 036 Old Isotope N -2 N -1 N N +1 N +2 CAPTUREDECAYCAPTUREDECAY  + or E L E C T R O N  New Isotope

SUMMARY Summarize Objectives with students. FEN-BET-I764 Rev. 037