Properties and Observation

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Properties and Observation
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Properties and Observation

• Science is a way of thinking and doing, and
  observation is an important component of the
  doing of science.

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Properties and Observation

• All scientific observations are either
  qualitative or quantitative in nature.

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Properties and Observation

• A qualitative observation is the recognition and
  description of a property (a fact or an
  occurrence) by using the senses.

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Properties and Observation

• Qualitative observations include
• Color
• Clarity
• Texture
• Odor
• Taste
• Sound
• Malleability
• Ductility
• Brittleness
• Luster
• Conductivity

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Properties and Observation

• A quantitative observation is a measurement or a
  count.
• A measurement requires an instrument and a system
  of measurement.

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Properties and Observation

• Quantitative observations include
• Mass
• Length
• Volume
• Density
• Temperature
• Specific Heat
• Melting Point
• Boiling Point
• Heat of Fusion

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Properties and Observation

• ALL PROPERTIES ARE DETERMINED THROUGH
  OBSERVATION!

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Properties and Observation

• All properties can be categorized in various
  ways. One way is to group properties as either
  being intensive or extensive.

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Properties and Observation

• An intensive property is one that is true
  regardless of the quantity present.
• As such, intensive properties are sometimes
  called identifying properties.

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Properties and Observation

• A diamond has a set of intensive properties that
  are different from quartz.

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Properties and Observation

• Diamond can burn but quartz cannot burn.

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Properties and Observation

• Diamond has a hardness of 10 on Mohs scale but
  quartz is 7.5.

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Properties and Observation

• Diamonds density is 3.52 g/cm3 but quartzs
  density is 2.65 g/cm3.

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Properties and Observation

• Diamonds melting point is 35500C but quartzs
  melting point is 1670oC.

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Properties and Observation

• Diamonds specific heat is 509 J/kgoC but
  quartzs specific heat is 670 J/kgoC.

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Properties and Observation

• A gold has a set of intensive properties that are
  different from pyrite (fools gold).

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Properties and Observation

• An extensive property is one that depends on the
  quantity present.
• Extensive properties alone can NOT be used to
  identify an unknown.

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Properties and Observation

• The sugar and salt samples below could have the
  same mass.
• The sugar and salt samples above could have the
  same volume.

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Properties and Observation

• A chemical property is a characteristic that can
  only be observed when trying to change the sample
  into something completely new.

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Properties and Observation

• Silver reacts with sulfur compounds to form
  tarnish but stainless steel does not react with
  sulfur compounds to form tarnish .

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Properties and Observation

• Hydrogen burns (reacts with oxygen) to form water
  but helium does not burn.

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Properties and Observation

• Copper does NOT react with hydrochloric acid but
  copper DOES reacts with nitric acid.

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Properties and Observation

• ALL CHEMICAL PROPERTIES ARE INTENSIVE.
• A lot of hydrogen burns exactly the same as a
  little bit of hydrogen!

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Properties and Observation

• A physical property is a characteristic that can
  be observed without changing the sample into
  something new and different.

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Properties and Observation

• Massing the silver, gold, and bronze medals does
  not change the silver, gold, and bronze.

• Even if the medals were bent in half, the pieces
  would still be made of silver, gold, and bronze.

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Properties and Observation

• A gold crowns volume can be found by water
  displacement without changing the gold.
• Even if the crown were hammered
  down flat, the gold
  would still be gold.
• Even if the crown were melted
  down, the gold would still
  be gold.

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Properties and Observation

• All of the elements can be classified based on
  their properties.
• The easiest classification scheme is to group the
  elements as metals or nonmetals.

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Properties and Observation

• The metals are found on the left and in the
  center of the Periodic Table.

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Properties and Observation

• A metal is an element that is usually gray in
  color and a solid at room temperature.

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Properties and Observation

• A metal is an element that is usually a good
  conductor of heat and electricity.

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Properties and Observation

• A metal is an element that is usually malleable
  and ductile.

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Properties and Observation

• A metal is an element that is usually lustrous
  (shiny).

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Properties and Observation

• A metal is an element that loses electrons
  (oxidizes) in chemical reactions.

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Properties and Observation

• The nonmetals are found on the upper right of the
  Periodic Table.

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Properties and Observation

• A nonmetal is an element that varies in color and
  varies in phase at room temperature.

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Properties and Observation

• A nonmetal is an element that is usually a poor
  conductor of heat and electricity.

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Properties and Observation

• Nonmetals are usually brittle.

Nonmetals break when struck with a hammer.
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Properties and Observation

• Nonmetals usually tend to gain electrons during
  chemical reactions.

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Properties and Observation

• The metalloids are found along the zig-zag line
  on the Periodic Table.
• B, Si, Ge, As, Sb, and Te

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Properties and Observation

• A metalloid is an element that has both metallic
  and nonmetallic properties.

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Properties and Observation

• Metalloids are sometimes called semimetals.

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Properties and Observation

• Metalloids are semiconductors of electricity.