inside the nucleus a.notebook
TRANSCRIPT
Inside the nucleus a.notebook
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Atomic Nucleus
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Atomic Nucleus and Isotopes
• Atoms of a nucleus consist of protons and neutrons and these are called NUCLEONS.
Atoms are neutral (# of protons = # of electrons)
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Descriptors
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Definion: Isotope • atoms with the same atomic number
( same number of protons) but different atomic mass ( # of protons +
# of neutrons)
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Notaon Represents element
Eg) carbon isotopes
C – 12
C 13
C 14
6 p + 6 n
6 p + 7 n
6 p + 8 n
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Binding Energy• ‐atomic nucleus consists of neutrons and protons
Strong nuclear force
Strong force
‐ holds protons and neutrons within a nucleus
‐ Overcomes repulsive Fe between protons
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The other strong force
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Binding Energy• Energy needed to break a nucleus apart
• Eb = Enucleons ‐ Enucleus
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Binding Energy• Determined by mass defect (difference in mass of individual nucleons and mass of the given nucleus)
• Calculated using
• NOTE: Einstein’s formula shows energy is directly related to mass.
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Key: MASS DEFECT
<The difference in mass is called the mass defect
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Atomic Mass Unit (u)Masses are too small to be measured in kg
1/12 the mass of a carbon‐12 atom
u = 1.66 x 10‐27 kg
E=1u x c2 = energy of one atomic mass unit
E = 1.492 x1010 J
= 9.31 x 108 eV or 931 MeV
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ExampleDetermine the binding energy of sodium – 23, which has a mass of 22.989969 u.
• Mass of nucleus = 22.989969 u
• Mass of proton = 1.007825
• Mass of a neutron = 1. 008665 u
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Soluon: 1.
3.
2.
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Binding Energy of Elements• The stability of different nuclei can be compared
by dividing the binding energy by the number of nucleons in the nucleus.
• The greater the binding energy per nucleon, the more stable a nucleus is.
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Binding Energies of Elements
Atomic Mass Number
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Assignment• Read Text Secon 16.1 p. 790 – 796
• Workbook p. 313
• Textbook p. 796 #1, 3, 7, 8