RAD 254 Chapter 3 The Structure of Matter

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RAD 254 Chapter 3The Structure of Matter

• Basic considerations of the atom
• -The atom is the smallest part of an element that
  has all the properties of that element

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112 total elements

• 92 are natural
• 20 are artificial

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Rutherford-Bohr

• Ernest Rutherford and Niels Bohr combination
  model of the atom is what we use today
• Nucleus and orbital electron shells surrounding
  the nucleus

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Atoms may combine

• Can combine to form MOLECULES
• Chemical compound new substance formed when two
  or MORE atoms of diff. elements combine
• Covalent bond sharing outer electrons among two
  atoms
• Ionic bond atoms attracted to each other due to
  opposite charges

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Atoms Molecules

• Smallest particle of an element is an atom
• Smallest particle of a compound is a molecule
• Atoms consist of 3 main parts electrons, protons
  and neutrons
• Mass of an atom is expressed in atomic mass units
  (AMUs)
• Nucleons protons () and neutrons (no charge)

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Electron shells

• Electrons only exist in certain shells K,L,M,N,
  etc where K shell is the 1 shell, L is 2 and
  so on this equals the MOST that can exist in
  any one shell not that they DO HAVE THAT MANY!
• The number of electrons in the outer shell tells
  which group and period it exists in the periodic
  table

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Electron Binding Energy

• The binding force or gravitational pull of an
  electron toward the nucleus.
• Is greatest the CLOSER the shell is to the nucleus

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Varied of mass and atomic

• ISOTOPE same number of protons BUT different
  of neutrons
• ISOBAR different of protons and neutrons BUT
  same total of nucleons
• ISOTONES same of neutrons but different of
  protons
• ISOMER same atomic number and same atomic mass
  number exist at different energy states due to
  differing nuclear arrangements

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RADIOACTIVITY

• Emission of particles and energy in order to
  become stable
• Can be emission of alpha, beta or gamma
• Particulate radiation is alpha or beta
• alphahelium nucleus 2 protons, two
  neutrons
• beta an electron emitted from the nucleus
  of a radioactive atom

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ELECTROMAGNETIC RADIATION

• Gamma rays or X-rays
• NO MASS
• NO charge
• Travel the speed of light
• 3 X 1010 cm/sec
• 3 X 108 m/sec

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