Elements and Compounds

Elements and Compounds

1. The Periodic Table

   • The first 20 elements:
     • 1 - Hydrogen - H
       • Non- metal
       • 2 - Helium - He
         • Non- metal
         • 3 - Lithium - Li
           • Metal
           • 4 - Beryllium - Be
             • Metal
             • 5 - Boron - B
               • Semi- metal
               • 6 - Carbon - C
                 • Non- metal
                 • 7 - Nitrogen - N
                   • Non- metal
                   • 8 - Oxygen - O
                     • Non- metal
                     • 9 - Fluorine - F
                       • Non- metal
                       • 10 - Neon - Ne
                         • Non- metal
                         • 11 - Sodium - Na
                           • Metal
                           • 12 - Magnesium - Mg
                             • Metal
                             • 13 - Aluminium - Al
                               • Metal
                               • 14 - Silicon - Si
                                 • Semi- metal
                                 • 15 - Phosphorus - P
                                   • Non- metal
                                   • 16 - Sulfur - S
                                     • Non- metal
                                     • 17 - Chlorine - Cl
                                       • Non- metal
                                       • 18 - Argon - Ar
                                         • Non- metal
                                         • 19 - Potassium - K
                                           • Metal
                                           • 20 - Calcium - Ca
                                             • Metal
   • Other Common Elements:
     • 29 - Copper - Cu
       • Metal
       • 26 - Iron - Fe
         • Metal
         • 79 - Gold - Au
           • Metal
           • 82- Lead - Pb
             • Metal
             • 47 - Silver - Ag
               • Metal
               • 30 - Zinc - Zn
                 • Metal
                 • 80 - Mercury - Hg
                   • Metal
                   • 53 - Iodine - I
                     • Non- metal
                     • 35 - Bromine - Br
                       • Non- metal
                       • 50 - Tin - Sn
                         • Metal

2. Elements

   • They are pure substances made up of only one type of atoms
     • Pure substance means that it cannot be separated physically, and it is the same regardless of the source
       • Compounds are also pure substances, but they are made up of two or more different elements chemically bound together in a definite ratio
   • Cannot be decomposed into more substances by chemical means
   • Some exist as two atoms chemically bonded together (diatomic molecules)
     • Molecules can be made of different elements or the same- compounds have to be different

3. Atoms

   • Smallest part of whole matter
   • Made up of protons, electrons and neutrons
     • Protons and neutrons are in the nucleus, and the electrons orbit the nucleus
     • Symbols and Relative Mass:
       • Proton - P - 1
         • Positive
         • Neutron - n - 1
           • Neutral
           • Electron - e - 1/2000
             • Negative

4. Our Changing View of the Atom

   • "Atoms are the building blocks of matter" - Early Greek philosophers - 400 B.C.E
     • "Negative electrons are embedded in a sea of positive charge" - J.J Thompson - 1898-1903
       • "Positive charge is located within a central nucleus" - Ernest Rutherford - 1911
         • "Electrons are in circular orbits with quantized energy levels" - Neils Bohr - 1913
           • "Electrons occupy regions of space whose shape is described by complex mathematical equations" - Quantum Mechanics - Modern Model
           • The Bohr Model:
             • Electrons in shells
               • Can be up to 2 electrons in the 1st shell, up to 8 electrons in shells 2 and 3, and up to 18 in 4th shell
               • Number of electrons= atomic number