Elements and Compounds

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Elements and Compounds

• And distinguishing between atoms and molecules

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ELEMENTS

• Pure substances
• Cannot be decomposed
• The building blocks of all matter
• There are 113 known elements

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Examples
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COMPOUNDS

• Pure Substance
• Made from combining elements
• Not all combinations of elements are compounds,
  some are mixtures
• Can be decomposed into simpler substances
• Have a definite composition
• a fixed number of elements

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Example

• H2O contains 2 parts H and 1 part O it is known
  as water
• H2O2 contains the same type of elements, hydrogen
  and oxygen, however, it does not have the same
  number of elements. It is hydrogen peroxide.
• Each compound has a fixed number of elements

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Examples
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ATOMS

• The smallest possible unit of an element
• An element only contains one type of atom

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MOLECULES

• Particles made of two or more atoms
• The smallest particle of a substance that retains
  the properties of the substance

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Self Check
Homogeneous Mixture
Compound
Heterogeneous Mixture
Homogeneous Mixture
Compound
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Classifying Matter
Compound
Heterogeneous
No
Uniform Properties??
Yes
Fixed Composition?
No
Yes
Yes
More than one element??
No
Homogeneous
Element