Chemistry Review

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Chemistry Review

• Moles, Molarity, and Formulas

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Moles

• Mole amount of a substance
• Avogadros number 6.02 x 1023
• 1 Mole of a substance Formula mass of a
  substance
• 1 mole of a substance 6.02 x 1023 particles of
  a substance
• 1 mole of a substance _at_ STP 22.4 L

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Molarity

• Molarity (M) is a measure of the concentration
  of a solution
• Molarity mole of a substance/1 dm3 of total
  solution
• 1 dm3 1 L

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Chemical Formulas

• Chemical formulas are written based on the number
  of valence electrons needed to balance the charge
  of the compound.
• You must remember your polyatomic ions!!
• Criss cross method is the easiest to use take
  the oxidation number of the positive ion and drop
  it down to become the subscript of the negative
  ion the oxidation number of the negative ion
  becomes the subscript for the positive ion

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Chemical Formulas cont

• Mg Cl MgCl2
• Formula mass is calculated by the number of each
  atom times its atomic mass
• Mg 1 atom _at_ 24 amu Cl 2 atoms _at_ 35 amu
  -?MgCl2 94 amu

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Naming Rules

• Ionic - m/nm write out positive ion and change
  ending of negative ion to ide
• Ionic m/polyatomic write out the positive ion
  and the polyatomic ion no change
• Ionic - multiple oxidation metal / nm or
  polyatomic write name of metal with the roman
  numeral following then write the negative ion
  according to rules above

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Covalent

• Use Greek prefixes for the number of atoms within
  the compound - exception do not use mono- on
  the first element in the compound
• Mono Penta Nona
• Di Hexa Deca
• Tri Hepta
• Tetra Octa

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Acids

• Hydrogen nonmetal use hydro and change the
  ending of the negative ion to ic
• Hydrogen polyatomic ion no hydro used if
  polyatomic ion ends in
• -ate change to ic
• -ite change to -ous

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Molarity by Dilution

• If you have a known concentration of a solution
  and you need to dilute it use
• M1 V1 M2 V2