Atomic Structure

• inner shell


  Innermost electron shell of an atom
• element


  A pure substance made up of one type of atom
• outer shell


  Outermost occupied electron shell of an atom
• PERIODIC TABLE


  Tabular arrangement of the chemical elements
• mass number


  The total number of protons and neutrons in the nucleus of an atom
• atomic number


  The number of protons in the nucleus of an atom
• Particles


  • Proton
  • Neutron
  • Electron
• Relative Charges of particles


  • +1
  • 0
  • -1
• Relative Mass


  • 1
  • 1
  • Approx. 1/1836 (Negligible)
• Location in Atom


  • In the nucleus
  • In the nucleus
  • Orbiting the nucleus, in shells/energy levels
• Atoms are listed in atomic number (proton number) order within the periodic table
• The proton number gives the identity of the atom
• Isotopes


  Forms of the same element that contain equal numbers of protons but different numbers of neutrons
• Group (vertical column) number

  Number of electrons in the outer shell
• Period (horizontal row) number

  Number of occupied electron shells in the atom
• Nuclear symbol


  Represents an element
• Atom


  Basic structure is a central nucleus surrounded by electrons which orbit around the nucleus in rings that we call shells
• Particles that make up the nucleus

  • Protons
  • Neutrons
• Protons and neutrons


  • Have the same mass, with a relative mass of 1
  • Protons have a positive charge of 1+
  • Neutrons have no charge (are neutral)
• Nuclear symbol


  Represents an element
• Electrons


  • Have a relative mass of 1/1836
  • Have a negative charge of -1
• Atomic number

  Tells us how many protons the atoms of that element have
• Mass number

  Tells us the total number of neutrons and protons in that atom