What is a compound? How are compounds made?

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What is a compound?How are compounds made?
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Chemical Bonds

• When valence electrons of elements are gain,
  lost, or shared between different atoms to create
  substances with unique chemical properties.
• When this happens COMPOUNDS ARE FORMED.
• So, what is a compound?

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Compounds

• Are substances made from elements and are held
  together by sharing, losing, or gaining electrons

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There are two kinds of bonding

• Ionic
• Covalent
• What is ionic bonding?
• When two or more ions are held together by the
  electrical attractions between them.

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Ionic Bonding

• This type of boning occurs between non-metals. It
  only occurs if the overall energy change for the
  reaction is favorable ( that is the bonded atoms
  have a lower energy than the free ones.
• The larger the energy change, the stronger the
  bond.

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Covalent Bonds

• It is characterized by the sharing of electrons
  between two or more atoms..
• What is a molecule?
• Molecules are formed when atoms share electrons,
  molecules are made of covalent bonds.

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What is a chemical formula?

• (also known as a molecular formula) is a concise
  way of expressing information about the atoms
  that constitute a particular chemical compound.
• For example,

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Do you know what this is?
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Chemical Formula

• CH4

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How many ?
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How would you write it?

• C 6H12 O6
• Glucose
• Now lets count atomsHandout 1

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What is a chemical reaction?

• Process in which the physical and chemical
  properties of the original substance changes
• a change in energy
• a re-arrangement of atoms

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A chemical reaction has

• Reactants what enters the chemical reaction
• Products what results from the chemical reaction
• And there is always a change in energy

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Reactions can be

• Exothermic
• Endothermic

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Types of Chemical reactions

• Synthesis when two or more substances combine to
  form a new more complex substance
• Example

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Decomposition

• When a more complex substance brakes down in to
  simpler ones

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Single replacement

• Is a chemical reaction in which an uncombined
  element replaces and element that is part of a
  compound
• Example

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Single replacement
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Double replacement

• It is when different atoms in 2 different
  compounds replace each other, in other words,
  when tow compounds react forming two new products

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Double replacement