Chapter Two Notes Atoms, Molecules, Ions by bmd18385

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									  Chapter Two Notes
Atoms, Molecules, & Ions
 1.   The Early History of Chemistry
 2.   Fundamental Chemical Laws
 3.   Dalton’s Atomic Theory
 4.   Early Experiments to Characterize the
      Atom
 5.   Modern View of Atomic Structure
 6.   Molecules and Ions
 7.   Introduction to the Periodic Table
 8.   Nomenclature
    2.1 Early History of Chemistry
                   5000 BC
► And  I have filled him with the spirit of God,
 in wisdom and ability, in understanding and
 intelligence, and in knowledge, and in all
 kinds of craftsmanship, to devise skillful
 works, to work in gold, and in silver, and in
 bronze, and in cutting of stones for setting
 and in carving of wood, to work in all kinds
 of craftsmanship.             Exodus 31: 3-5
   2.1 Scientific Method

                                 Find patterns,
Observations and               trends, and laws –
  experiments                      Formulate
                                   hypothesis




                 Test hypothesis
               and propose theory
                 Continue cycle.
2.2 Fundamental Chemical Laws
► Lawof Conservation of Mass (Antoine
 Lavoisier/1743-1794) Total mass of the
 materials present after a chemical reaction
 is the same as the before the reaction.
► Lawof Definite Proportion (Joseph Proust/
 1754-1826) A given compound always
 contains exactly the same proportion of
 elements by mass.
                       Sample Exercise 2.1
         2.3 Dalton’s Atomic Theory
            John Dalton (1766-1844)
► Each  element is made up of time particles called
  atoms.
► The atoms of a given element are identical; the
  atoms of different elements are different in some
  fundamental way.
► Chemical compounds are formed when atoms of
  different elements combine with each other. A
  given compound always has the same relative
  numbers and types of atoms.
► Chemical reactions involve reorganization of the
  atoms – changes in the way they are bound
  together. The atoms themselves are not changed.
     2.3 Gay-Lussac & Avogadro
       (1778-1850) & (1776-1856)
► Gay-Lussac  contributed to the methods of
  developing formulas for compounds by
  experiments with the way parts of gases
  combined with each other (hydrogen and
  oxygen to form water vapor, for instance.
► Avogadro proposed that at the same
  temperature and pressure, equal volumes of
  different gases contain the same number of
  particles.
      2.4 Early Experiments to
 Characterize the Atom (1898-1911)
► The   Electron – JJ Thomson – Plum Pudding
   Cathode Ray Tube Experiments
► Themagnitude of the charge on an electron –
  Robert Millikan
   Milikan Oil Drop Experiments
► Radioactivity – Henri Becquerel – alpha (α), beta
  (β), and gamma (γ )particles.
► The Nucleus – Ernest Rutherford – dense center of
  positive charge
   Gold Foil Experiments
   2.5 The Modern View of Atomic
      Structure: An Introduction
► The atom consists of a
 tiny nucleus (with a      Particle Mass Charge
                                      (amu)
 diameter of about
 10^-13 cm) and            Electron   5.486 x   1-
                                      10^-4
 electrons that move
                           Proton     1.0073    1+
 about the nucleus
 (with an average
 distance of about 10^-    Neutron 1.0087 neutral
 8 cm)

                            Sample Exercise 2.2
       2.6 Molecules and Ions
► ChemicalBonds are the forces that hold
 atoms together in compounds
   Covalent Bonds form bonds by sharing
    electrons. These special compounds are called
    molecules.
   Molecules are represented by:
    ►Chemical   Formula
    ►Structural Formula
    ►Space Filling Model
    ►Ball and Stick Model
  2.6 Molecules and Ions cont’d.

► ChemicalBonds are the forces that hold
 atoms together in compounds

   Ionic bonds result from the electrostatic
    attraction of cations (positively charges ions)
    and anions (negatively charged ions). Electrons
    are transferred from one atom to another.
             2.7 An Introduction to the
                   Periodic Table
►   Organized according to the atomic number
►   Most of the elements are metallic in nature (tend to lose electrons and
    become cations)
►   The nonmetals are located in the upper right corner.
►   The vertical columns are called groups or families. The horizontal rows
    are called periods.
         I                                                                        VIII


             II                                         III   IV   V   VI   VII




                       Transition Metals
    2.7 An Introduction to the
      Periodic Table cont’d.
         Group 1         Alkali Metals
         Group 2         Alkaline Earth Metals
         Group 7         Halogens
         Group 8         Noble Gases
         Elements in the same group behave similarly in
            chemical reactions.
I                                                                        VIII


    II                                         III   IV   V   VI   VII




               Transition Metals
 2.8 Naming Simple Compounds
► Binary Ionic Compounds (Type I)
 contain a cation always written first in the
 formula and an anion.
   The cation is always named first and the anion
    second.
   A monatomic (one atom) cation takes its name
    from the name of the element.
   A monatomic anion is named by taking the root
    of the element name and adding –ide. Thus Cl-
    become chloride.
                           Sample Exercise 2.3
 2.8 Naming Simple Compounds cont’d
► Binary Ionic Compounds (Type II) In
 these compounds, the cation can form more
 than one type of positive charge. There are
 two systems:
   Systematic method names utilize a Roman
    numberal to indicate the charge on the cation.
   An older method is sometimes used and you
    may encounter this. The ion with the higher
    charge has a name ending in -ic , and the one
    with the lower charge has a name ending in –
   ous.
                       Sample Exercise 2.4
 2.8 Naming Simple Compounds cont’d
► Ionic  Compounds with Polyatomic Ions
  are ions that contain covalently bonded
  atoms that perform together as an ion.
  They are assigned special names that must
  be memorized.
► Table 2.5, page 62 in your text is a list that
  should be committed to memory.

                      Sample Exercise 2.5
  Memorize
 2.8 Naming Simple Compounds cont’d
► Binary Covalent Compounds (Type III)
 are formed between two nonmetals.
   The first element in the formula is named first,
    using the full element name.
   The second element is named as if it were an
    anion.
   Prefixes are used to denote the numbers of
    atoms present.
   The prefix mono- is never used for naming the
    first element.
  2.8 Naming Simple Compounds cont’d

► Prefixes Used to     Prefix   #   Prefix   #

  Indicate Number in
                       mono-    1 hepta-     7
  Chemical Names
                       di-      2 octa-      8
                       tri-     3 nona-      9
                       tetra-   4 deca-      10
      Sample           penta-   5 undeca-    11
    Exercise 2.6       hexa-    6 dodeca-    12
 2.8 Naming Simple Compounds cont’d
► Acids– an acid can be viewed as a
 molecule with one or more hydrogen ions
 attached to an anion.
   If the acid does not contain an oxygen, the acid
    is name with the prefix hydro- and the suffix –ic
    such as hydrochloric acid.
   If the acid does contain an oxygen, the name is
    formed from the root name of the anion with a
    suffix of –ic (anion ending in –ate) or –ous
    (anions ending in –ite) depending on the name
    of the anion. Sufuric acid and sulfurous acid.

                       Sample Exercise 2.7

								
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