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Pure Substances, Elements, Compounds, and Mixtures

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Pure Substances, Elements, Compounds, and Mixtures What are pure substances? PURE SUBSTANCES Substances made of one kind of material with a unique set of chemical and ... – PowerPoint PPT presentation

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Title: Pure Substances, Elements, Compounds, and Mixtures


1
Pure Substances, Elements, Compounds, and Mixtures
2
(No Transcript)
3
What are pure substances?
  • PURE SUBSTANCES ? Substances
  • made of one kind of material with a
  • unique set of chemical and physical
  • properties. Elements and
  • compounds are pure substances.

4
What is an element?
  • ELEMENT? a
  • pure substance
  • that cannot be
  • broken down into
  • simpler
  • substances

5
  • There are slightly more than 100 known
  • chemical elements that are arranged on the
  • periodic table developed by Dimitri
  • Mendelev. Each element is abbreviated
  • with one or two symbols. The 1st letter is
  • capitalized and the 2nd is not. Each symbol
  • represents the English name, old name, or
  • Latin name of the element.

6
EXAMPLE
  • (Latin) Aurum-Gold Au
  • (English) Oxygen O
  • (Old) Natrium Sodium - Na

7
  • Some elements are named after
  • famous scientists, countries, states,
  • and planets.
  • (101) Mendelevium scientist
  • (32) Germanium Germany
  • (98) Californium California
  • (92) Uranium - Uranus

8
What are compounds?
  • COMPOUNDS ? 2 or more elements
  • chemically combined
  • EX magnesium oxide (MgO2)
  • Magnesium Oxygen

9
Separating Compounds
  • Compounds can be separated by chemical
  • means because they are chemically
  • combined. Compounds can be broken down
  • by electrolysis. Electrolysis literally means
  • to tear apart with electricity. It is a
  • technique using an electric current to pass
  • through a substance. If the substance is a
  • compound, it may be broken down into the
  • separate elements that form it.

10
EX H2O (water)
  • If an electric current passes through
  • the compound, the compound will
  • break down into the two elements
  • hydrogen and oxygen.

11
What is a mixture?
  • MIXTURES ? a blend of two or more
  • pure substances

12
Types of Mixtures
  • Heterogeneous Mixture ? a mixture that has
    visibly different parts
  • Homogeneous Mixture ? mixtures that do not
    contain visibly different parts
  • (Hetero- and Homo- are two Greek roots that
  • mean different and same.)

13
Heterogeneous vs Homogeneous
14
Separating Mixtures
  • Mixtures can be separated by
  • decantation, filtration, crystallization,
  • distillation, chromatography.

15
Decantation
  • Decantation ? gentle pouring off of a liquid
    without disturbing a solid sediment
  • EXAMPLE
  • cleaning a fish tank and leaving behind most of
    the sand, shells, and plants
  • drinking coffee and leaving small residue of
    coffee grounds behind in a cup

16
Filtration
  • Filtration ? passage
  • of a liquid or gas
  • through a porous
  • substance for the
  • purpose of removing
  • suspended solids.
  • A mixture of water
  • and an insoluble
  • substance like sand
  • can be separated by
  • filtering.

17
Crystallization
  • Crystallization refers to the formation of solid
    crystals from a homogeneous solution. It is
    essentially used as a solid-liquid separation
    technique.

18
Distillation
  • Distillation ? the process in which a liquid is
    evaporated and the vapors condensed
  • The solution is heated until it boils. The liquid
    with the lowest boiling point boils first and
    becomes a vapor (gas). The vapor is cooled in the
    condenser until the temperature falls below the
    boiling point when it condenses back into a
    liquid which is collected in a container.

19
Chromatography
  • Chromatography ? process used to separate
    mixtures using a solvent (water) that carries a
    solute (ink) up a strip of paper

20
  • Heterogeneous mixtures can be separated by
    physical means such as filtration.
  • Homogeneous mixtures can be separated by
    distillation, crystallization, chromatography.
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