Elements, Compounds, and Mixtures

1
Elements, Compounds, and Mixtures
2
Mixtures

• Mixture - blend of two or more pure substances
• Saltwater is mixture of salt and water
• can be separated physically, such as boiling

3
Types of Mixtures

• Heterogeneous mixtures - mixtures have visibly
  different parts
• Example granite - heterogeneous mixture of
  different types of minerals
• Homogeneous mixtures - mixtures do not contain
  visibly different parts
• Example Saltwater separated into pure water and
  solid salt

4
(No Transcript)
5
Separating the Components of a Mixture

• Special equipment and techniques developed to
  separate mixtures
• Do not cause a chemical change, such as
  electrolysis.

6

• Heterogeneous mixtures - solids and liquids can
  be separated by filtration
• Homogeneous mixtures - techniques such as
  distillation, crystallization, and chromatography
  (not filtration!)

7
Filtration
Crystallization
Distillation
Chromatography
8
Elements and Compounds

• Element - substance that cannot be separated into
  simpler substances by a chemical change
• As of right now, nearly 118 elements are known to
  exist.
• Named for famous scientists, countries, states,
  planets and original latin

9

• Elements - abbreviated for convenience, called
  element symbols.
• Symbols consist of one or two letters.

10

• First letter - always capitalized
• Second letter - if present, is never capitalized
• Some symbols are straight from the name, whereas
  some symbols are derived from their Latin names.
• Hydrogens symbol ? H,
• Golds symbol ? Au, for the Latin name of Aurem.

11

• To help organize elements, chemists developed the
  periodic table of elements.

12
(No Transcript)
13
Compounds

• Compound - two or more elements combine in a
  chemical reaction
• compound is substance that contains two or more
  elements combined in fixed proportion
• NaCl
• H2O
• C6H12O6

14

• Chemical formula - the symbols for the elements
  that make up the compounds For example
• Magnesium, Mg, and oxygen, O, combine to form
  magnesium oxide, MgO
• Symbols - letter of the chemical alphabet
• Chemical formulas - the words of chemical language

15
Distinguishing between Elements and Compounds

• Elements and compounds are pure substances
• Every substance has a unique set of chemical and
  physical properties
• Not easy to tell when substance is an element or
  compound!

16
Distinguishing between Elements and Compounds

• Compounds can be broken down into separate
  elements, whereas elements cannot be broken down
• Water is compound that can be separated through
  electrolysis, or passing an electric charge
  through it
• The results are hydrogen gas and oxygen gas,
  which are elements

17
(No Transcript)