Atoms

Atoms

1. Elements

   • Periodic table
     • organized by atomic number
       • atomic number: number of protons
         • proton: positively charged particle in the nucleus of an atom
           • neutron: neutrally charged particle in the nucleus of an atom
             • isotopes
               • same number of protons, different number of neutrons
             • electron: negatively charged particle in the energy levels of an atom
   • Metals
     • transition metals
       • multivalent
         • can have different number of electrons in outermost shell
     • forms cations when charged
       • electrostatic attraction
     • lustrous
     • malleable
     • ductile
     • good conductors
   • Non-metals
     • covalent bond: a bond between non-metals and involves sharing electrons
       • molecule
         • molecular compounds
           • forms crystals
           • low melting/boiling points
           • poor conductors of electricity when dissolved in water
     • noble gases
       • element group
       • fully occupied outermost shell
         • stable
           • low reactivity
     • forms anions when charged
       • ionic compound
         • transfer of electrons
         • forms crystals
         • high melting points
         • brittle
         • conducts electricity when dissolved in water
           • free floating ions
     • brittle

2. none are lost or gained in a chemical reaction

   • Law of Conservation of Mass
     • Antoine Lavoisier
   • chemical change processes