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A Look at NuclearScience and Technology

Larry Foulke

2.1 Atomic and Nuclear Physics The Einstein Connection

Getting to know the atom

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Image Source: See Note 1

The Einstein Connection

E=mc2

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The Atom

Image Source: See Note 2

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The Atom Electrons Negatively charged, light-weight particles that orbit the nucleus. Involved in forming chemical bonds with other atoms

Protons Positively charged, heavy particles in the atomic nucleus. Number of protons determines the element and all physical

properties of atom.

Neutrons Charge-less, heavy particles in atomic nucleus Neutrons stabilize the nucleus. To few or too many neutrons will

make a nucleus unstable.

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The Atom Atoms are identified byAtomic Number (Z): Number of protons in the

nucleus. Determines what element the atom is.

Atomic Mass (A): Total weight of the atom, equal tonumber of protons + number of neutrons. (A=Z+N)

Notation!"#

Atomic Mass

Atomic Number(optional)

Element(or Chemical)

Symbol

Examples

11H 42He 23592U

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Isotopes

Nuclide A type of atom characterizedby the number of protons and neutronsin the nucleus of every atom of this type.

Isotopes Atoms with the samenumber of protons (same element) butcontaining different numbers of

neutrons.

Nuclides with same atomic number butdifferent atomic masses.

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238UraniumU

237UraniumU

236UraniumU

235UraniumU

234UraniumU

233UraniumU

232UraniumU

238

92

237

92

236

92

235

92

234

92

233

92

232

92

!

!

!

!

!

!

!Isotopes

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TritiumTorH

DeuteriumDorH

HydrogenH

31

31

2

1

2

1

1

1

Isotopes

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Mass -- Atomic Mass Unit (amu)1 amu = 1/12 mass of Carbon-12 atom

= 1.660565 x 10-27kg

Proton = 1.007276 amu Electron = 0.000549 amu

Neutron = 1.008665 amu

Energy -- Electron Volt (eV)1 eV = 1 electron charge x 1 volt

= 1.60219 x 10-19Joules1 keV = 1,000 eV

1 MeV = 1,000,000 eV

Mass and Energy Units

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The Nucleus Nucleus

Protons & Neutronstightly packed togetherinto a (roughly) spherical

shape.

How Tightly Packed? dnucleus/ datom= 6.4!10-5 Vnucleus/ Vatom= 2.6!10-13

= 0.000000000026%

Image Source: See Note 3

31 pm = 31!10-12m

4He

1.98 fm= 1.98!10-15m

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Nucleus Size Comparisons If atomic volume is the size

of a medium classroom:

30!30!10= 9000 cu. ft.

The nucleus would be thesame size as an a grain ofsand

~8 mils = ~0.2 mm

11

Atomic Diameter = 100 m

Nuclear Diameter = 6.4 mm

Image Sources: See Notes 4 and 5

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1. Public domain:http://en.wikipedia.org/wiki/File:Einstein-formal_portrait-35.jpg

2.

Creative Commons:http://en.wikipedia.org/wiki/File:Atom_diagram.png

3. Creative Commons:http://en.wikipedia.org/wiki/File:Helium_atom_QM.svg

4. GNU license:http://en.wikipedia.org/wiki/File:AmFBfield.svg

5. Creative Commons:http://commons.wikimedia.org/wiki/File:Ballpoint-pen-parts.jpg

Image Source Notes