atomic structure

• Atomic number


  The number of protons in an atom
• Neutral atom


  The number of protons equals the number of electrons
• Mass number


  The number of protons plus the number of neutrons
• Electron shells


  • The first shell can contain 2 electrons, the second shell can contain 8 electrons, the third shell 8 electrons and the fourth shell contain 8 electrons

  
• As atomic number increases by 1

  1. Number of protons and electrons each increase by 1

  2. Number of neutrons do not show a set pattern

  3. If electrons cannot fit in a particular shell, they go to a higher level

  
• Electron configuration


  Describes where electrons are located around the nucleus of an atom

  
• Electron configuration of lithium

  • 2, 1
• OXYGEN has atomic number 8, mass number 17, 8 protons, 9 neutrons, and 8 electrons