1 • Ions combine to form ionic compounds . • Ionic compound – a compound formed by reacting a metal (cation) with a nonmetal (anion) • Properties of ionic compounds High melting points Conduct electricity If melted If dissolved in water Section 4.11 Compounds That Contain Ions
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1 Ions combine to form ionic compounds. Ionic compound – a compound formed by reacting a metal (cation) with a nonmetal (anion) Properties of ionic compounds.
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1
• Ions combine to form ionic compounds.
• Ionic compound – a compound formed by reacting a metal (cation) with a nonmetal (anion)
• Properties of ionic compounds High melting points Conduct electricity
If meltedIf dissolved in water
Section 4.11
Compounds That Contain Ions
2
• Ionic compounds are electrically neutral.• The charges on the anions and cations in the
compound must sum to zero.
Section 4.11
Compounds That Contain Ions
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• Write the cation element symbol followed by the anion element symbol.
• The number of cations and anions must be correct for their charges to sum to zero.
• Write the cation element symbol followed by the anion element symbol.
• The number of cations and anions must be correct for their charges to sum to zero.
Formulas for Ionic Compounds
Section 4.11
Compounds That Contain Ions
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Concept Check
A compound contains an unknown ion X and has the formula XCl2. Ion X contains 20 electrons. What is the identity of X?
a) Ti2+
b) Sc+
c) Ca2+ d) Cr2+
Section 4.11
Compounds That Contain Ions
Z = # of e- + positive chargeor
Z = # of e- - negative charge
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Concept Check
A member of the alkaline earth metal family whose most stable ion contains 36 electrons forms a compound with bromine. What is the correct formula for this compound?
a) CaBr2
b) KrBrc) RbBr
d) SrBr2
Section 4.11
Compounds That Contain Ions
• Ionic compounds are electrically neutral.
• The charges on the anions and cations in the compound must sum to zero.
Type II Binary Ionic Compounds• Contain Metal Cation + Nonmetal Anion
o Transition metals can have various oxidation numbers or charges
For example iron can be either Fe2+ or Fe3+
• Metal cation name is the metal name followed by a Roman Numeral in parentheses to indicate its charge– Determine charge on metal from anion charge– Common Type II cations in Table 5.2
¶ Nonmetal anion named by changing the ending on the nonmetal name to -ide
• When anion contains oxygen (oxyanion) the root name of the anion is used, along with– ic acid for oxyanions ending in –ate– ous acid for oxyanions ending in –ite
– H2SO4 sulfate ion Sulfur ic acid– HNO3 nitrate ion Nitr ic acid– HNO2 nitrite ion Nitr ous acid
• For Type III compounds, use the prefixes to determine the subscripts
• For Type I, Type II, polyatomic Compounds and Acids– Determine the ions present– Determine the charges on the cation and anion– Balance the charges to get the subscripts