22.3 Notes Part D

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22.3 Notes Part D

• Covalent Formulas Naming

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Objectives

• Write formulas and names for covalent compounds

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Covalent compounds

• Made of just nonmetals
• Share electrons
• Smallest piece is a molecule
• Cant be held together because of opposite
  charges
• Cant use charges to figure out how many of each
  atom

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Covalent/Molecular compounds

• Ionic compounds use charges to determine how many
  of each element.
• Molecular compounds name tells you the number of
  atoms.
• Uses prefixes to tell you the number

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Naming Covalent Compounds

• Prefix element name Prefix element name-ide
• The last vowel of the prefix is dropped when the
  second element begins with a vowel as in
  pentoxide
• No double vowels when writing names (oa oo)
• Often the prefix mono- is omitted from the first
  element when naming

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Examples

• Carbon dioxide CO2
• Dihydrogen monoxide H2O
• Dinitrogren pentasulfide N2S5
• Tricarbon tetrafluoride C3F4

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Name These

• N2O
• NO2
• Cl4O7
• NBr3
• BaCl5

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Writing formulas for Covalent Compounds

• Simply write the chemical symbol
• Subscript is derived from the prefix
• Mono 1, di 2, tri 3, ect

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Write formulas for these

• diphosphorus pentoxide
• tetraiodide nonoxide
• sulfur hexaflouride
• Carbon tetrahydride
• phosphorus trifluoride

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Hydrates

• An ionic compound that has water chemically
  attached to its ions and written into its
  chemical formula

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Hydrates pg. 708

• These same prefixes are used when naming the
  hydrates previously discussed.
• The main ionic compound is named the regular way,
  but the number of water molecules in the hydrate
  is indicated by the Greek prefix.
• Chemical formula H2O

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Hydrates

• BeBr2 3 H2O
• Calcium nitride hexahydrate

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In-Class Assignment/Homework

• 22.3 reinforcement WKT