Department of Chemistry

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• Department of Chemistry
• CHEM1010 General Chemistry
• Instructor Dr. Hong Zhang
• Foster Hall, Room 221
• Tel [phone]
• Email hzhang_at_tntech.edu

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CHEM1010/General Chemistry_______________________
__________________Chapter 2. (L9)-Introduction
to Atoms

• Todays Outline
• ..Revisit to matter classification
• Operational classification vs. theoretical
  classification
• ..Modern Periodical Table
• Group A and Group B
• Metals, non-metals, and in between
  (metalloids), noble gases
• ..Basic language of todays modern chemistry
• Chemical letters 114 atoms discovered so far
• Chemical molecules Chemical words
• Chemical reactions Chemical sentences
• ..Questions about atoms Their components and
  structure?

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Chapter 2. (L9)-Introduction to Atoms

• Revisit to matter classification
• ..Two kinds of definitions in science
• Operational definitions Those in which a
  definition is given by a certain practical
  operation without referring to its meaning in a
  relevant context
• Theoretical definitions Those in which a
  definition is formulized based on theoretical
  ideas or models and thus each definition has
  theoretical meaning in a relevant context

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Chapter 2. (L9)-Introduction to Atoms

• Revisit to matter classification
• ..Two kinds of definitions in science
• Example Define qualified apples of a certain
  kind for Standard A apples
• -Operational definition Any apples that can
  pass a net with holes of the size of 3.5 inch3.5
  inch and also remain in a net with holes of the
  size of 3 inch3 inch
• This means the Standard A apples have a size in
  between 3 inch and 3.5 inch and any apple with
  this size will be classified as a Standard A
  apple.
• This definition calls for an operation which
  can be performed in practice.

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Chapter 2. (L9)-Introduction to Atoms

• Revisit to matter classification
• ..Two kinds of definitions in science
• Example Define qualified apples of a certain
  kind for Standard A Apples
• -Theoretical definition Any apple of species B
  with T type of cells containing F type of genes.
• This definition involves certain theoretical
  concepts and models and has clear theoretical
  meanings to those who know species of plants, the
  meaning of T type cells and F type genes.

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Chapter 2. (L9)-Introduction to Atoms

• Revisit to matter classification
• ..Two kinds of definitions in chemistry
  regarding matter
• Operational definition Matter is classified as
  compounds and elements as pure substances and
  mixtures of different pure substances put
  together physically
• -Compounds Those that can be further decomposed
  or separated by chemical changes into simpler
  substances with a fixed ratio in mass
• -Elements Those that cannot be further
  decomposed or separated into simpler substances
  by chemical changes
• So, you can distinguish between compounds and
  elements by conducting some chemical operations,
  examples
• water (H2O) hydrogen gas (H2) oxygen gas
  (O2)
• mercury oxide (HgO) mercury (Hg) oxygen gas
  (O2)

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Chapter 2. (L9)-Introduction to Atoms

• Revisit to matter classification
• ..Operational definitions in chemistry regarding
  matter
• -Operational definitions for matter
  classification were historically created and used
  by experimental chemists
• -Operational definitions may encounter confusion
  because the definitions depends on how you
  conduct the chemical operations.
• -If you conduct the chemical operations in
  different ways under different conditions, you
  may end up with different results, that is, your
  simpler substances depend on the chemical
  operations. Example
• H2O H2 O2 O2 sunlight O O

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Chapter 2. (L9)-Introduction to Atoms

• Revisit to matter classification
• ..Two kinds of definitions in chemistry
  regarding matter
• Theoretical definition Matter is composed of
  atoms and molecules
• Molecules are composed of either the same kind
  of or different kinds of atoms combined together
  in a certain ratio (example H2O, O2)
• So, these definitions are based on the theory of
  atoms as formulized by Dalton.

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Chapter 2. (L9)-Introduction to Atoms

• Revisit to matter classification
• ..Theoretical definitions in chemistry regarding
  matter
• -The theoretical definitions have much more
  clarity and consistency. Now, any kind of matter
  can fall into the theoretical definitions.
• -No operational variations and differences are
  involved to cause confusion.
• -In a sense, atoms are special cases of
  molecules. We can say an atom is a molecule
  composed of only one atom. In this sense,
  chemistry is about molecules (different
  molecules, small or large) or chemistry is the
  science of molecules.

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Chapter 2. (L9)-Introduction to Atoms

• Revisit to matter classification
• ..Match between operational definitions and
  theoretical definitions in chemistry for matter
  Hybrid definitions
• Here, the terminologies from both historical
  operational definitions and modern theoretical
  definitions are hybridized together
• -An element is a pure substance composed of only
  one kind of atom
• -A compound is a pure substance composed of
  atoms of different elements combined in definite
  ways.

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Chapter 2. (L9)-Introduction to Atoms

• Revisit to matter classification
• ..To a chemist, a substance always is a pure
  substance, either an element or a compound.
• ..You need to realize that the traditional,
  historical operational definitions and the hybrid
  definitions may not always converge or be
  consistent with each other.
• Example Ozone (O3), 2O3 3O2
• So, according to the operational definitions,
  then its a compound but, according to the
  hybrid definitions, it is then an element.

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Chapter 2. (L9)-Introduction to Atoms

• Revisit to matter classification
• ..The definition for element in our textbook is
• An element is one of the fundamental substances
  from which all material things are constructed.
• -This definition seems to refer to atoms as
  elements, or refer to both atoms and the
  substances composed of one kind of atoms (so the
  definition is not quite clear).
• ..Any way, the point is that the terminology
  element may be referred to with slightly
  different meanings by different authors and
  chemists as demonstrated in our discussion.

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Chapter 2. (L9)-Introduction to Atoms

• Modern Periodic Table
• ..First, the elements as listed in the table
  actually refer to atoms of each of the elements.
  In a sense, perhaps, it may be more appropriately
  called the Periodic Table of Atoms.
• ..Most of the properties listed in the table for
  each element or atom are the properties or
  characteristics of each of the atoms.
• ..In some Periodic Tables, some physical
  properties listed (such as boiling point, melting
  point, density, etc.) are those of the elements
  in their simplest forms that can exist normally
  under the conditions near ground at the Earth
  surface (e.g, for oxygen, it is O2 not O3).

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Chapter 2. (L9)-Introduction to Atoms

• Modern Periodic Table
• ..New elements are still being discovered from
  time to time. Currently, 114 elements with 109
  elements officially named.
• In a textbook published in 1986, element 104 was
  listed as Rf (1969) and Ku (1964), element 105
  was listed as Ha (1970) and Nl (1967), and
  element 106 did not have any name.
• In a book published in 1989, element 104 was
  list as Ru and element 105 as Ha, elements
  106-109 were listed in the names as Unh, Uns,
  Uno, and Une, respectively.
• In a book in 1996, elements 104-109 were listed
  as Rf, Ha, Sg, Ns, Hs, and Mt, respectively.
• In our textbook published in 2004, elements
  104-109 are listed as Rf, Db, Sg, Bh, Hs, and Mt,
  respectively.

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Chapter 2. (L9)-Introduction to Atoms

• Modern Periodic Table
• ..The modern Periodic Table is arranged by
  atomic number (its meaning will be discussed in
  next chapter), rather than atomic mass as in the
  history.
• ..The modern Periodic Table is called a long
  version table.
• ..It has more than 114 atoms or elements, each
  in a box basically with atomic number, chemical
  symbol, and atomic mass in amu (relative atomic
  mass based on carbon at 12), and many tables with
  a host of characteristics and properties of atoms
  and some properties of the elements.

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Chapter 2. (L9)-Introduction to Atoms

• Modern Periodic Table
• ..The vertical columns that list elements with
  similar chemical and chemical properties are
  called groups numbered from I to VIII and divided
  into A groups and B groups (example, IA, IIIB).
• ..A groups are for the representative or
  main-group elements
• ..B groups are for the transition elements in
  between the two areas of main-groups.
• ..Inner transition elements are the Lanthanide
  series and the actinide series that appear at the
  bottom of the table.
• ..The horizontal rows are called periods. These
  periods are related to the energy levels for
  electrons in atoms (discussed in next chapter).
  

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Chapter 2. (L9)-Introduction to Atoms

• Modern Periodic Table
• ..87 elements are metals (special physical
  properties and appearance) in Groups IA, IIA,
  parts of Groups IIA to VIIA, and the B groups
• ..Characteristic physical properties of metals
• -malleability (beaten into thin sheets, Al
  foil)
• -ductility (stretched into wires, copper wire)
• -thermal and electrical conductivity

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Chapter 2. (L9)-Introduction to Atoms

• Modern Periodic Table
• ..17 elements are non-metals appeared in the
  upper right corner of the table.
• ..Physical and chemical properties of
  non-metals
• generally just opposite to those of metals
• example bad thermal and electrical
  conductivity (insulator)
• ..Metalloids Part of the non-metal elements
  boarding the metals and non-metals in the right,
  like Si, Ge, As, which are semiconductors
  (excellent for computer chips).
• ..Noble gases Group VIIIA, very inert
  chemically

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Chapter 2. (L9)-Introduction to Atoms

• Modern Periodic Table
• ..The Periodic Table of Elements is an excellent
  summary, compilation, and generalization of the
  observations and facts in chemistry.
• ..Now, we are asking these following questions
• Why the elements show these periodic
  regularity? What is the rationale behind? How can
  we explain the periodicities? Would Daltons
  atomic theory be sufficient to offer the
  explanations? And many more related questions.
• ..Next chapter will answer some of the
  questions.

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Chapter 2. (L9)-Introduction to Atoms

• From modern Periodic Table to chemical language
• ..The Periodic Table of Elements provide the
  basic letters for chemistry 114 letters
  representing 114 different kinds of atoms.
• ..Each molecule composed of either the same or
  different atoms combined in a certain ratio would
  be regarded as one chemical word. Thus, each
  particular substance is one chemical word.
• ..Then, a chemical reaction between different
  chemical molecules to form new molecules may be
  regarded as a chemical sentence.

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Chapter 2. (L9)-Introduction to Atoms

• Chemical language
• ..From now on, all discussion on chemistry will
  be based on the basic chemical language, that is,
  we are now seeing the material world or the
  things or matter as molecules
• ..Now, we only see molecules and changes of
  molecules from one kind to another. This is our
  modern chemical view on matter.
• ..We need to know what things or substances are
  what molecules. We need to study various
  molecules, their physical and chemical
  properties, their structures, and their
  interactions with each other. These are what we
  will discuss on chemistry from now on, and these
  are what chemistry about.

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Chapter 2. (L9)-Introduction to Atoms

• New questions
• ..Now, we have learned fundamental facts about
  chemistry, the three basic laws of chemistry, and
  the grand summary of chemical facts in the
  Periodic Table, and we also learned Daltons
  atomic theory, which is so successful in
  explaining the three laws of chemistry. It seems
  that chemistry is pretty good.
• ..This illusion cannot survive new discoveries
  and observations in chemistry and physics.
• ..The new findings have been driving modern
  science as well as chemistry going forward
  endlessly. Lets go to Chapter 3 next time.

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Chapter 2. (L8)-Introduction to Atoms

• Quiz Time
• The Periodic Table was created as a result of
• (a) Daltons personal effort only
• (b) Mendeleevs personal work only
• (c) the Russian chemists efforts only
• (d) many many repeatable observations in
  chemistry made by many chemists and their
  continuous efforts to make an order for the
  various chemical facts.

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Chapter 2. (L8)-Introduction to Atoms

• Quiz Time
• The basic chemical language in modern chemistry
  is based on
• (a) the stars in the night sky
• (b) the basic letters of a specific human
  language
• (c) the basic music notes
• (d) the 114 atoms each denoted by a symbol.

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Chapter 2. (L8)-Introduction to Atoms

• Quiz Time
• The number of the kinds of atoms in chemistry is
  
• (a) fixed for ever
• (b) variable all the time
• (c) is determined by textbooks
• (d) fixed for a certain time until a new atom or
  element is discovered.

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Chapter 2. (L8)-Introduction to Atoms

• Quiz Time
• The periodicity of chemical and physical
  properties of elements appears in the Periodic
  Table in
• (a) horizontal periods
• (b) the lanthanide series
• (c) the actinide series
• (d) vertical columns (groups) in which the
  elements share similar properties.

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Chapter 2. (L8)-Introduction to Atoms

• Quiz Time
• In the Periodic Table, non-metals appear mainly
  in
• (a) left side B groups
• (b) left side A groups
• (c) middle B groups
• (d) right side A groups.