16.1 Nuclear Decay(SLN) - hschemsolutions.com DecayModes(SLN).pdfA proton absorbs an electron. This...
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1 Nuclear Chemistry 16.1 Modes of Nuclear Decay The Nucleus The nucleus contains: • Protons (+ charge) • Neutrons (no charge) Protons and neutrons and known as nucleons . U 238 92 238 nucleons 92 protons 238 – 92 = 146 neutrons Nuclear Decay An unstable nucleus undergoes a change and a reduction in energy to become more stable. Four types of nuclear decay. 1) Alpha Decay 2) Beta Decay 3) Positron Emission 4) Electron Capture Ex) Alpha (α) Decay The nucleus emits an alpha particle. Ex) Uranium-238 undergoes alpha (α) decay. Number of nucleons must balance (234 + 4 = 238) Number of protons must balance (90 + 2 = 92) 238 4 92 2 U + He → Beta (β) Decay A high speed electron is ejected from a neutron. This turns the neutron into a proton. + - + - + Neutron Proton Electron 1 1 0 0 1 1 n p + e − → → Ex) Beta (β) Decay An electron is ejected from a neutron. This turns the neutron into a proton. Ex) Iodine-131 undergoes beta (β) decay. Number of nucleons must balance (131 + 0 = 131) Number of positive charges must balance (54 – 1 = 53) 131 0 53 1 I + e − → www.hschemsolutions.com © 2009 High School Chem Solutions. All rights reserved. Sample Copy of Students' Lecture Notes
Transcript of 16.1 Nuclear Decay(SLN) - hschemsolutions.com DecayModes(SLN).pdfA proton absorbs an electron. This...
1
Nuclear Chemistry 16.1
Modes of Nuclear Decay
The NucleusThe nucleus contains:• Protons (+ charge)• Neutrons (no charge)
Protons and neutrons and known as nucleons.
U238
92
238 nucleons
92 protons238 – 92 = 146 neutrons
Nuclear Decay
An unstable nucleus undergoes a change and a reduction in energy to become more stable.
Four types of nuclear decay.1) Alpha Decay2) Beta Decay3) Positron Emission4) Electron Capture
Ex) Alpha (α) Decay
The nucleus emits an alpha particle.Ex) Uranium-238 undergoes alpha (α) decay.
Number of nucleons must balance (234 + 4 = 238)
Number of protons must balance (90 + 2 = 92)
238 4 92 2U + He→
Beta (β) Decay
A high speed electron is ejected from a neutron. This turns the neutron into a proton.
+- + -+
Neutron Proton Electron
1 1 00 1 1n p + e−→
→
Ex) Beta (β) DecayAn electron is ejected from a neutron. This turns the neutron into a proton.
Ex) Iodine-131 undergoes beta (β) decay.
Number of nucleons must balance (131 + 0 = 131)
Number of positive charges must balance (54 – 1 = 53)
131 053 1I + e−→
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Positron EmissionBeta Positive (β+) Decay
A high speed positron is ejected from a proton. This turns the proton into a neutron.
+-
+- ++
Proton Neutron Positron
+
1 1 01 0 1p n + e+→
→
Ex) Positron Emission (β+) Decay
A positron is ejected from a proton. This turns the proton into a neutron.
Ex) Fluorine-17 undergoes beta (β+) decay.
Number of nucleons must balance (17 + 0 = 17)
Number of positive charges must balance (8 + 1 = 9)
17 09 1F + e+→
Electron Capture
A proton absorbs an electron. This turns the proton into a neutron.
+-
+ -+Proton electron Neutron
1 0 11 1 0p + e n− →
→
Ex) Electron CaptureA proton absorbs an electron.
This turns the proton into a neutron.Ex) Xenon-118 undergoes electron capture.
Number of nucleons must balance (118 + 0 = 118)
Number of positive charges must balance (54 – 1 = 53)
118 0 54 1Xe + e − →
Gamma Ray (γ) Emission
The nucleus is unstable immediately after any type of decay.
γ
Emits high energy electromagnetic radiation to reduce energy.
Nucleus’ stability increases after
this energy is released.
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