Covalent Compounds

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Covalent Compounds

• Chapter 4 5

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• A covalent compound contains atoms that share
  electrons to satisfy the octet rule.
• (They do not transfer electrons like ionic
  compounds.)

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• Covalent compounds are formed from two nonmetals.
• (Remember that ionic compounds are formed between
  a metal and a nonmetal)

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P2O5

• Ionic or covalent?

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SnS2

• Ionic or covalent?

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CF4

• Ionic or covalent?

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• A molecule or molecular substance is an uncharged
  group of two or more atoms held together by
  covalent bonds.

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Properties of covalent compounds
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1.

• Most are gases or liquids at room temperature.

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2.

• Much lower melting and boiling points
• Why? We dont need to break any bonds

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3.

• Soft, squishy, malleable (bendable)
• Why? They can move very easily without bonds
  between them

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4.

• A lot contain H C which are both flammable
  sooooo a lot of covalent compounds are flammable

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5.

• Do not conduct electricity of water
• Why? No ions around

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6.

• Most are not soluble in water
• Like dissolves like

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Naming covalent compounds

• N2O4
• What is the name?

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1.

• Write the name of the element farthest to the
  left.
• If they are both in the same group, write the one
  closest to the bottom.

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2.

• Write the name of the second compound but change
  the ending to ide.

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3.

• Add a prefix to indicate the number of the
  subscript (see p. 168 in TB)

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• 1 mono-
• 2 di-
• 3 tri-
• 4 tetra-
• 5 penta-
• 6 hexa-

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• Exceptions-do not put mono on the first element
• Do not put o-o or o-a together. Get rid of the
  first letter

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NO
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NO

• Nitrogen Monoxide

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NO2
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NO2

• Nitrogen dioxide

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N2O
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N2O

• Dinitrogen monoxide

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N2O5
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N2O5

• Dinitrogen pentoxide

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Some Common Names

• H2Owater
• NH3ammonia
• CH4methane
• C2H6ethane
• C3H8propane
• C4H10--butane

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Writing formulas from names

• Carbon Tetrachloride
• What is the formula?

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1.

• Write the symbols in the order given in the name

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2.

• The prefix will tell you the subscript to write
• If there is no prefix, the subscript is one, and
  you dont have to write the one.

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• Organic compounds contain carbon
• Inorganic compounds do not contain carbon