CHEM 001C Lecture Notes - Nuclear Chemistry, Unified Atomic Mass Unit, Nuclear Reaction

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CHEM 001C Lecture 19: Nuclear Chemistry

●Nuclear Binding Energy

○The mass of a helium-4 nucleus is 4.0015 amu

■The mass of β neutrons + β protons is 4.0γβ0 amu

○E = mcβ

■If the protons and neutrons in the helium-4 nucleus are separated, energy

would need to be absorbed

■When the helium-4 nucleus forms, 0.0γ05 amu is lost as energy released

■Nuclear binding energy: mass reduction upon forming helium-4; mass

converted to energy (E = mcβ)

○Note: binding energy is maximized at mass number = 60 amu

■Smaller



nuclei → energy released



when nuclei are formed



(fusion)

■Larger



nuclei (mass # > 60) → energy released



when nuclei decay

(fission)

●Nuclear power plants involve fission

●Isotopes/ Atomic Numbers

○Nuclear chemistry is based on the properties of nuclei with different sizes (atomic

number) and forms of elements with different numbers of neutrons (isotopes)

■Nuclear chemistry: the study of the properties and changes of atomic

nuclei

■Nuclear reaction: a reaction that changes the atomic nucleus

●βγ8

9βU → 4

βHe + βγ4

90Th

○Nucleons: protons + neutrons

●Radioactivity

○Radioactivity: the spontaneous decay and emission of radiation from an unstable

nucleus

■radiation is strongly deflected toward the (+) electrode

■radiation is undeflected

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Document Summary

The mass of a helium-4 nucleus is 4. 0015 amu. The mass of neutrons + protons is 4. 0 0 amu. If the protons and neutrons in the helium-4 nucleus are separated, energy would need to be absorbed. When the helium-4 nucleus forms, 0. 0 05 amu is lost as energy released. Nuclear binding energy : mass reduction upon forming helium-4; mass converted to energy (e = mc ) Note : binding energy is maximized at mass number = 60 amu. Smaller nuclei energy released when nuclei are formed ( fusion ) Larger nuclei (mass # > 60) energy released when nuclei decay ( fission ) Nuclear chemistry is based on the properties of nuclei with different sizes (atomic number) and forms of elements with different numbers of neutrons (isotopes) Nuclear chemistry : the study of the properties and changes of atomic nuclei. Nuclear reaction : a reaction that changes the atomic nucleus.

Related Questions

On forming the nuclide from the protons, neutrons and electrons,the mass loss per nucleon for the is 0.00759 amu, whereas that foris 0.00944 amu. This means that:
A) undergoes nuclear fission
B) is more stable than
C) thirteen nuclei could react to form one nucleus
D) is more stable than
E) weighs more than

What total energy is released when 0.75 grams of 235U undergofission if each atom averages
3.2 Ã 10-11 J of energy released?
A) 1.45 Ã 1013 J
B) 6.01 Ã 1031 J
C) 6.15 Ã 1010 J
D) 6.15 Ã 107 J
E) 1.45 Ã 1010 J

Bombardment of by a deuteron, , forms a proton and an isotope whichhas a mass number of ________ and an atomic number of________.
A) 75, 32
B) 75, 33
C) 73, 32
D) 76, 33
E) 74, 34

Nuclear Decay Equations

Learning Goal:

To predict the products of alpha emission, beta emission, positron emission, and electron capture.

Radioactivity is the spontaneous emission of radiation from an unstable nucleus. There are five major types of radioactive decay:

Alpha (Î±) radiation consists of helium nuclei. The helium nucleus is a small particle containing two protons and two neutrons (42He).

Beta (Î²) radiation consists of electrons. In nuclear equations, the standard format for representing a beta particle using superscripts and subscripts is 0â1e.

Positron emission results from the conversion of a proton in the nucleus to a neutron. The ejected positron is a particle that has the same mass as an electron but an opposite charge. In nuclear equations, the standard format for representing a positron using superscripts and subscripts is 01e .

Electron capture is the capture of an inner shell electron by a proton in the nucleus. The process emits gamma (Î³) radiation and results in a proton converting to a neutron. Gamma radiation consists of high-energy electromagnetic radiation.

Gamma (Î³) radiation consists of high-energy radiation, and contains no particles and thus they have no mass. In nuclear equations, the standard format for representing gamma radiation using superscripts and subscripts is 00Î³.

Balancing a decay equation

There are two main rules to remember when balancing nuclear equations:

The total of the superscripts in the reactants and products must be the same.

The total of the subscripts in the reactants and products must be the same.

For an isotope of an element, the superscripts are mass numbers, and the subcripts are atomic numbers:

Mass number â¶ AAtomic number â¶ Z X âµ Chemical symbol

Where the mass number (A) is the sum of the number of proton and number of neutrons in the nucleus, atomic number (Z) is the number of protons in the nucleus, and chemical symbol (X) is the symbol of the specific element.

Part A

Identify the nuclide produced when americium-241 decays by alpha emission:

241 95Amâ42He + ?

Express your answer as an isotope using prescripts.

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Part B

Identify the nuclide produced when phosphorus-32 decays by beta emission:

3215Pâ 0â1e + ?

Express your answer as an isotope using prescripts.

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Part C

Identify the nuclide produced when fluorine-18 decays by positron emission:

18 9Fâ01e + ?

Express your answer as an isotope using prescripts.

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Part D

Identify the nuclide produced when thallium-201 decays by electron capture:

201 81Tl+ 0â1eâ00Î³ + ?

Express your answer as an isotope using prescripts.

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CHEM 001C Lecture Notes - Nuclear Chemistry, Unified Atomic Mass Unit, Nuclear Reaction

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