©1998 RCBrill. All rights reserved


Program 22

Lesson 3.7

1.  Questions
2.  Coming Up
3.  Objectives
4.  Introduction
5.  What is matter
6.  Substance
7.  Elements and Atoms
8.  Classification of Matter
9.  States of Matter
10.  Physical and Chemical Properties
11.  Physical vs. Chemical Change
12.  Energy and Chemical Reactions
13.  Chemistry
14.  Summary

Text References

Spielberg & Anderson: none

Booth & Bloom 223-224;226-227

1.  Questions

  1.  Define matter

  2.  What is a "substance"?

  3.  Discuss the separation and union of the concepts of atom and element.

  4.  Distinguish between the following pairs:

   1.4.1.  element/compound;

   1.4.2.  heterogeneous/homogeneous;

   1.4.3.  mixture/pure substance;

   1.4.4.  substance/element

  5.  Characterize each of the three states of matter in terms of volume and shape.

  6.  What are liquid crystals?

  7.  Distinguish between chemical and physical properties?

  8.  Describe two physical properties and two chemical properties

  9.  How can you distinguish between chemical change and physical change?

  10.  Describe two examples of a chemical change and a physical change.

  11.  Decide if each of the following is a chemical or physical change:

   1.11.1.  cooking an egg

   1.11.2.  rusting of iron

   1.11.3.  breaking of glass

   1.11.4.  melting of ice

   1.11.5.  fading of paint in the sun

  12.  Is heat always involved in a chemical reaction?  In a physical reaction?  Explain.

  13.  What is the difference between an exothermic reaction and an endothermic reaction?

2.  Coming Up

  Before we're done with this lesson we will have answered the question, What is Matter as we distinguish between substances and elements and learn about atoms and elements.  We will learn how matter can be classified and we will learn about the physical characteristics of the states of matter before we study chemical and physical changes and the energy involved in chemical reactions.  We will conclude with a brief description of the science of chemistry and its goals.

3.  Objectives

  1.  Distinguish between substance and element

  2.  Define matter and its distinguishing properties

  3.  Describe the classification of matter according to purity and separability

  4.  State the physical characteristics of three fundamental states of matter

  5.  Distinguish between chemical and physical changes

4.  Introduction

  4.1.  The study of matter is as old as the study of the stars, from the chipping of stone tools to the use of fire for smelting metals from their ores, to more sophisticated firing of pottery and the isolation of specific chemicals for dies, medicines and intoxicants.

  4.2.  Our modern world knows tens of thousands of different substances, each with a unique set of properties

  4.3.  The discoveries of the components of matter is a story which will occupy our efforts for the remainder of the course as we trace the development of the atomic paradigm from its beginnings.

   4.3.1.  Along the way we will see how the Newtonian paradigm is used to help in the discovery of atoms and their properties, their composition, and their nature.
   4.3.2.  leads to modern atomic theory
   4.3.3.  provides connection between chemistry and Newtonian paradigm
   4.3.4.  explains chemical, physical, and thermal properties of matter
   4.3.5.  unites all of physical science under one paradigm

5.  What is matter?

  5.1.  hard to define, easy to recognize

   5.1.1.  usually know it when we see it
   5.1.2.  look at some examples  air  clouds  iron  water  thoughts  ideas  emotions

  5.2.  has mass and occupies space

  5.3.  obeys Newtonís laws

6.  Substance

  6.1.  general meaning of the word

   6.1.1.  it has "substance"
   6.1.2.  substantial

  6.2.  a substance is a particular kind of matter

  6.3.  unique properties distinguish one substance from another

  6.4.  some substances are also elemental

  6.5.  most substances are not elements

  6.6.  all other substances are combinations of elements

  6.7.  elements are a special class of substances

7.  Elements and Atoms

  7.1.  elements are the purest substances

  7.2.  pure (uncombined, native) forms are rare

   7.2.1.  most elemental substances do not occur naturally  mixtures (atmosphere, sea water)  compounds (chemical combinations)
   7.2.2.  a few elements occur uncombined  sulfur  carbon  metals:gold, silver, platinum, copper  oxygen and nitrogen are uncombined but well mixed

  7.3.  Greeks considered atoms and elements as separate concepts

   7.3.1.  rejected atoms, kept elements  different concept of element

  7.4.  modern concept of element has long evolution

   7.4.1.  from Aristotle's four elements through mystical alchemy

  7.5.  more and more elements were isolated

   7.5.1.  nine in 1500
   7.5.2.  about 50 in mid 1800s
   7.5.3.  80 - 85 a hundred years ago
   7.5.4.  a hundred or so known today

  7.6.  connecting elements with fundamental particles of matter is a modern concept

  7.7.  synthesis of previously unrelated concepts

   Strangely enough, no one made the connection between atoms and elements until the nineteenth century.  The concept of element was well established by then, but the marriage of the two concepts requires a special consideration.  This will be the subject of section 4 of the course.

  7.8.  required a new definition of both concepts

  7.9.  an important step in modern thought

8.  Classification of Matter


  8.1.  Heterogeneous

   8.1.1.  aggregates
   8.1.2.  mixtures which can be physically separated
   8.1.3.  individual constituents can be seen
   8.1.4.  examples:  beach sand, concrete, chocolate chip cookie

  8.2.  Homogeneous

   8.2.1.  Homogeneous Mixture (solution)  mixture can be separated by physical means  individual constituents cannot be identified  examples:  seawater, perfume
   8.2.2.  Pure  compound  substance which contains only one kind of molecule  example: water, alcohol  element  substance which contains only one kind of atom  example:  oxygen, copper, carbon

9.  States of Matter

  9.1.  gas

   9.1.1.  specific relationships between temperature, pressure and volume
   9.1.2.  properties helped to decipher the atomic nature of matter
   9.1.3.  variable shape
   9.1.4.  variable volume

  9.2.  solid

   9.2.1.  most solids are crystalline  atoms arranged in repeating pattern  called crystal lattice  crystal shapes not always apparent  fixed melting point for a given substance
   9.2.2.  others are glass or glassy solid  irregular groupings of atoms  no fixed melting temperature  gradually soften over wide temperature range  glass  tar  butter  liquid crystals  normally glassy state  weak alignments of atoms may be intensified or disrupted by heat or electricity  examples
   9.2.3.  fixed shape
   9.2.4.  fixed volume
   9.2.5.  crystalline or not

  9.3.  liquid

   9.3.1.  only water is naturally common on earth
   9.3.2.  most other liquids are man made and water based
   9.3.3.  unusual state  atoms are shifting groups of aligned atoms  chaotic, semiorganized state
   9.3.4.  variable shape
   9.3.5.  fixed volume

10.  Physical and Chemical Properties

  10.1.  Physical Properties

   10.1.1.  distinguishable with senses
   10.1.2.  qualitative and quantitative
   10.1.3.  taste, smell, shape, color, luster are qualitative
   10.1.4.  density, thermal expansion, conductivity, electrical resistance, specific heat, boiling and melting temperature, cleavage, crystal form are quantitative
    10.1.5.  intrinsic properties do not depend upon size, shape or location

  10.2.  Chemical Properties

The video program shows several demonstrations of chemical properties. Those are listed here as "demo".

   10.2.1.  chemical behavior with other substances  demo: zinc in copper nitrate (Zn in CuSO4)  demo: sodium in water (Na in H2O)
   10.2.2.  reaction to acids and bases  demo: zinc in hydrochloric acid ( Zn + HCl)  demo: calcium carbonate in hydrochloric acid (CaCO3 + HCl)  demo: sucrose in sulfuric acid (C6H12O6 and H2SO4)
   10.2.3.  reactions with solutions
   10.2.4.  combustibility  demo:  burning magnesium (Mg)
   10.2.5.  chemical stability

11.  Physical vs. Chemical Changes

  Most of the time changes can clearly be identified by one or more of the following criteria.  Only the fixed ratio method alone is both necessary and sufficient to distinguish alone.  It also requires precise experiments to determine.

  11.1.  reversibility

   11.1.1.  Physical Change  generally reversible  by thermal processes alone  ice <-->water <--> steam  can melt ice after freezing  salt dissolves in water  can reclaim salt by evaporating water
   11.1.2.  Chemical Change  generally not reversible  cannot uncook an egg by refrigeration  some may be reversed by chemical means  demo:  pH indicators  extraction of iron from ore is reverse of rusting

  11.2.  thermal processes

   11.2.1.  chemical changes give off or absorb heat
   11.2.2.  so do some physical reactions  change of state  dissolution
   11.2.3.  solutions become warmer or colder
   11.2.4.  combustion is a chemical change, solution is a physical change

  11.3.  composition

   11.3.1.  chemical changes produce new substances  product has very different properties from reactants  sodium chloride is neither metal or gas  water is not like either hydrogen or oxygen  demo: sodium sulfide and cadmium nitrate (NaS + Cd(NO3)2
   11.3.2.  physical change does not involve a change in composition  not always easy to tell

  11.4.  mixing ratios

   11.4.1.  physical changes occur in variable ratios  alloys or solutions are possible in various proportions  silver and gold will alloy in any proportion  salt will dissolve in various amounts of water  water and alcohol can be mixed in any proportion
   11.4.2.  chemical changes occur in fixed ratios  physical mixtures allow for infinite ratios  salt dissolves in water  water and alcohol mix  metals alloy  law of definite proportions is followed  chemical compounds have set formulas  a certain amount of iron always reacts with a certain amount of sulfur  chemical reactions "leave behind" excess material in original form

12.  Energy and Chemical Reactions

  12.1.  exothermic

   12.1.1.  "exo":  from, ie. exit
   12.1.2.  give off energy
   12.1.3.  combustion, dissolving sodium hydroxide
   12.1.4.  may require activation energy to initiate (like combustion)
   12.1.5.  demo:  dissolving sodium hydroxide in water (NaOH + H2O)

  12.2.  endothermic

   12.2.1.  "endo": into
   12.2.2.  absorb energy  demo:  dissolving ammonium chloride in water (NH4Cl + H2O)
   12.2.3.  used in ďcold packsĒ

13.  Chemistry


 13.1.  chemical properties of substances

 13.2.  elements and atoms

 13.3.  properties of chemical elements

 13.4.  reactions between elements

 13.5.  elemental makeup of substances

 13.6.  nature of chemical reactions

 13.7.  distinct from alchemy

  13.7.1.  alchemy:chemistry:: astrology:astronomy

14.  Summary

 In this program we have tried to show what matter is, how it is classified, and an overview of how it has changes over the years.  We also examined the distinction between physical and chemical properties and between physical and chemical change.

A brief description of the role of heat in chemical reactions was followed by brief survey of the science of chemistry, the topic of the final section of our journey down the river of scientific heritage.

This is the last lesson in part 3. In part 4 we will explore the theory of matter and see how atomic theory allows the Newtonian system to extend into chemistry, and finally explain the relationship between heat and motion.