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IONS AND IONIC COMPOUNDS. MONATOMIC IONS are atoms with a positive or negative charge. Taking away an electron from an atom gives a CATION with a positive charge Adding an electron to an atom gives an ANION with a negative charge . . PREDICTING ION CHARGES. In general
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IONS AND IONIC COMPOUNDS • MONATOMIC IONSare atoms with a positive or negative charge. • Taking away an electron from an atom gives a CATION with a positive charge • Adding an electron to an atom gives an ANION with a negative charge.
PREDICTING ION CHARGES In general • metals (Mg) lose electrons ---> cations • Charge = group number • nonmetals (F) gain electrons ---> anions • Charge = group number -8
-4 -3 -2 -1 +1 +2 Charges on Common Ions +3 By losing or gaining e-, atom has same number of e-’s as nearest Group 8A atom.
METALS M ---> n e- + Mn+ where n = periodic group Na+ sodium ion Mg2+ magnesium ion Al3+ aluminum ion Transition metals -->M2+or M3+ are common Fe2+ iron(II) ion Fe3+ iron(III) ion See Table 9.2 page 255
Transition Elements • Charges of 2+ and 3+ are common • Roman numeral indicates the charge of the ion • Classical Name – suffixes indicate charge (sort of) • ous means less • ic means more • See Table 9.2 page 255
Group 5A Group 6A Group 7A Group 4A C4-,carbide NONMETALS NONMETAL + n e- ------> Xn- where n = 8 - Group no. N3-, nitride O2-, oxide F-, fluoride S2-, sulfide Cl-, chloride Br-, bromide I-, iodide
POLYATOMIC IONS • Groups of atoms with a charge. • Names end in –ite or –ate • ite means less • ate means more MEMORIZEthe names and formulas in Table 9.3 page 257.
Polyatomic Ions NO3- nitrate ion HNO3 nitric acid
Polyatomic Ions NH4+ ammonium ion One of the few common polyatomic cations
Polyatomic Ions CO32- carbonate ion HCO3- bicarbonate ion hydrogen carbonate
Polyatomic Ions PO43- phosphate ion CH3CO2- acetate ion
Polyatomic Ions SO42- sulfate ion SO32- sulfite ion
Sodium The cation Naming Binary Ionic Compounds • Binary compounds are composed of two elements, a metal and a non-metal. • Place the name of the cation first and then the name of the anion. • Remember the –ide suffix. chlor ide The anion
Writing formulas for Binary Ionic Compounds • Write the symbol of the cation and the anion (include the charge) • Add whatever subscripts are needed to balance the charge • Use the criss-cross method • The charge of one ion becomes the subscript of the other. Don’t forget to reduce to the empirical formula.
Strontium sulfate The cation The polyatomic ion. Don’t change the name Naming Ternary Ionic Compounds • Ternary compounds are composed of three or more elements. • Place the name of the cation first and then the name of the anion. • Often end in –ite and -ate
Writing formulas for Ternary Ionic Compounds • Write the symbol of the cation and the anion (include the charge) • Add whatever subscripts are needed to balance the charge • Use parentheses when the compound contains more than one polyatomic ion • Use the criss-cross method
Naming Binary Molecular Compounds • Binary compounds are composed of two elements, two non-metals. • The name identifies the elements and how many of each atom there is in the compound. • Name the elements in the order they appear in the formula. • Use prefixes to indicate the number of each kind of atom. • Omit mono- when the name has only one atom of the first element. • Use the suffix –ide for the name of the second element.
9.3 Naming Binary Molecular Compounds
Name these compounds! • PBr3 • CrBr3 • N2O • Na2O • Cl4 • PbI4 • P2O3 • Fe2O3
Writing formulas for Binary Molecular Compounds • Use the prefixes in the name to determine the subscript of each element in the formula. Phosphorus pentafluoride
Naming Acids • Ionic compounds with unique properties • Contain one or more hydrogen atoms and produce H+ ions when dissolved in water • When the name of the anion ends in –ide , the acid name begins with hydro-. The stem of the anion has the suffix –ic and is followed by the word acid. • HCl hydrogen chloride • acid name – hydrochloric acid • When the anion name ends in –ite, the acid name is the stem of the anion with the suffix –ous, followed by the word acid. • H2SO3 hydrogen sulfite • Acid name – sulfurous acid • When the anion name ends in –ate, the acid name is the stem of the anion with suffix –ic followed by the word acid. • HNO3 hydrogen nitrate • Acid name – nitric acid
Naming Bases • Ionic compounds with unique properties • Produce OH- ions when dissolved in water • Named the same as other ionic compounds • Name of the cation followed by the anion.