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Matter
Learning Objectives
A checklist of concepts to learn and skills to master in this section.
Lecture Slides
Lecture Notes
Links
Internet sites and paper references for further exploration.
Frequently Asked Questions
Find an answer, or ask a question.
Glossary
Terms and definitions from the glossary are marked with an asterisk (*).
Quiz: Classifying properties
Classify properties as extensive, intensive, chemical, or physical.
/chem/senese/101/matter/classify-properties-quiz.shtml (9/12/98)

Quiz: Classifying matter
Classify matter as heterogeneous mixtures, homogeneous mixtures, compounds, or elements.
/chem/senese/101/matter/classify-matter-quiz.shtml (9/09/98)

Learning objectives

Lecture outline

This lecture introduces some of the basic vocabulary and notation that will be used in the remainder of the course. Classification of matter and technologies for separating mixtures are discussed.

Quiz Quiz
Classifying properties as extensive/intensive or chemical/physical

Properties of Materials

  • describe materials by listing their properties
  • chemical properties* vs. physical properties*.
  • intensive properties* vs. extensive properties*.

    Classifying properties as extensive or intensive. Extensive properties change when sample size changes; intensive properties don't.

    Beaker w/100 mL waterBeaker w/10 mL water
    Mass of water100.0 g10.0 g
    Volume of water0.100 L0.010 L
    Temperature of water25 °C25 °C
    Density of water1.00 g/mL1.00 g/mL

States of Matter

Gas Liquid Solid
Gas: free motion Liquid: flickering clusters Solid: vibrating lattice
  • low density
  • easy to expand/compress
  • fills container
  • high density
  • hard to expand/compress
  • takes shape of container
  • high density
  • hard to expand/compress
  • rigid shape
  • A phase is a region with homogeneous (uniform) properties
  • conversions between states are called "phase transitions" or "changes of state"

Classification of matter

uniform
properties?
yes
fixed
composition?
yes
chemically
decomposable?
yes
compound*
no no no
heterogeneous mixture* homogeneous mixture* element*
Quiz Quiz
Classifying matter

Pure substances

  • characteristics
    • percentage composition always the same from sample to sample
    • melt/boil at a characteristic temperature
      • note: some compounds decompose before melting or boiling!
  • two types
    • elements
      • not chemically decomposable into other elements
      • properties do not vary
molecular view of an element
molecular view of a compound

Elements

  • modern definition: elements are made of atoms that all have the same atomic number*
  • obtaining elements from compounds involves chemical change
    • electrolysis* decomposes some compounds into elements
    • some elements displace others from compounds
  • writing element symbols*
    • first 1-2 distinguishing letters in name used for symbol
    • only the first letter is uppercase!
    • memorize symbols derived from ancient names:
      Table 11 element symbols derived from ancient names.
      English name symbol ancient name
      antimony Sb stibium
      copper Cu cuprum
      gold Au aurum
      iron Fe ferrum
      lead Pb plumbum
      mercury Hg hydrargyrum
      potassium K kalium
      silver Ag argentum
      sodium Na natrium
      tin Sn stannum
      tungsten W wolfram

Classification of elements

  • periodic table compactly shows relationships between elements
  • features of the periodic table
    • Periods are horizontal rows on the table.
    • Groups (or families) are columns on the table.
      • elements in the same group are called congeners. They have similar chemical properties.
    • Blocks are regions on the table.
  • important groups:
    • alkali metals (Group IA, first column )
      • soft, extremely reactive metals
      • react with cold water to form hydrogen gas
      • form +1 ions
    • alkaline earth metals (Group IIA, second column):
      • soft, reactive metals
      • compounds are a major component of earth's crust
      • form +2 ions
    • halogens (Group VIIA, next-to-last column):
      • poisonous and extremely reactive nonmetals
      • fluorine and chlorine are yellow-green gases
      • bromine is a volatile red-brown liquid
      • iodine is a volatile blue black solid
      • all form -1 ions
    • noble gases (Group 0, last column)
      • all are monatomic gases
      • a. k. a. inert gases; almost completely unreactive
  • Important blocks:
    • transition metals are the elements in the region from the third to twelfth columns.
      • hard, dense metals
      • less reactive than Group IA and IIA
    • rare earth metals are the elements in the annex at the bottom of the table.
      • lanthanides (annex, top row)
      • actinides (annex, bottom row)
    • main group elements are all elements except the transition and rare earth metals.
      • group numbers end with "A"
    • metals, nonmetals, and metalloids (semimetals)
      • metallic properties
        • luster
        • malleability: can be hammered into thin sheets
        • ductility: can be drawn into wire
        • conduct heat and electricity well

Allotropes

  • one element can occur in several different forms ( allotropes)

    Common allotropes of oxygen and carbon. The most stable form at room temperature and pressure is shown in boldface.

    element allotrope
    oxygen O, nascent oxygen
    O2, oxygen gas
    O3, ozone
    carbon graphite
    diamond
  • gaseous elements commonly occur as diatomic molecules (except for the noble gases)

Mixtures

  • characteristics
    • percentage composition varies from sample to sample
    • components are chemically different and retain properties in a mixture
    • do not melt/boil at a definite temperature
  • two types
    • heterogeneous mixtures
      • components not uniformly mixed
      • more than one phase*
    molecular view of a heterogeneous mixture
    • homogeneous mixtures
      • components uniformly mixed
      • one phase
      • also called solutions
    molecular view of a homogeneous mixture

How separation technology was used to solve a deadly mystery

Separating mixtures

  • mixture's components have different properties
  • devise a process that selects components with certain properties
    • density, melting point, boiling point, solubility, reactivity, magnetism, polarity
  • some basic techniques
    • filtration: select components by particle size
    • floatation: select components by density
    • crystallization: select components by solubility
    • extraction: select components by solubility
    • distillation: select components by boiling point
    • chromatography: select components by affinity for a 'stationary phase'
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General Chemistry Online! Matter

Copyright © 1997-2005 by Fred Senese
Comments & questions to fsenese@frostburg.edu
Last Revised 07/25/05.URL: http://antoine.frostburg.edu/chem/senese/101/matter/index.shtml