The Atom

• Nucleus


  Center of atom; has protons (+) & neutrons (n)
• To calculate the # of neutrons in an element

  Subtract the atomic mass w/ the atomic number
• Atom - smallest unit of matter; maintains characteristics of an element
• Electrons (-)

  Negatively charged sub-atomic particle; mass of an electron is negligible/unimportant; number of electrons = number of protons
• Neutron (n)

  Sub-atomic particle w/ no charge; mass = to 1 atomic mass unit
• Periods in the Periodic Table

  • Period 2 = 2 valence shells, etc.
• Electron Cloud


  Region surrounding the nucleus, contains electrons (-)
• Groups in the Periodic Table

  • Group 1 = 1 valence electron, etc.
• Atoms combine through Sharing of Electrons

  Forming Covalent Bonding/Bonds
• Electrons behave as if in a 3D orbit
• Valence Electrons


  Outer most electrons; responsible for bonding
• Atoms combine through Transfer of Electrons

  Forming Ionic Bonding/Bonds
• Proton (+)


  Positively charged sub-atomic particle; number of protons = atomic number of an element