Page 107 - Theory and Problems of BEGINNING CHEMISTRY

96 INORGANIC NOMENCLATURE [CHAP. 6

NAMING IONIC COMPOUNDS
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6.9. Name NH 3 and NH 4 .
Ans. Ammonia and ammonium ion. Note carefully the differences between these names and these formulas.

6.10. How can a beginning student recognize an ionic compound?
Ans. If the compound contains the NH 4 ion or a metal it is most likely ionic. (It might have internal covalent
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bonds.) If it is a strong acid in water solution, it is ionic. Otherwise, it is covalent.

6.11. Name (a) CuO and (b)Cu 2 O.
Ans. (a) Copper(II) oxide (b) copper(I) oxide. This example again emphasizes the difference between the Arabic
numerals in a formula and the Roman numerals in a name.

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6.12. In naming NO 3 , professional chemists might say nitrate or nitrate ion, but in naming Na , they always
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say sodium ion. Explain the difference.
Ans. Nitrate is always an ion; sodium might refer to the element, the atom, or the ion, and so a distinction must
be made.

6.13. What is the difference in the rules for remembering charges on monatomic anions and oxyanions?
Ans. Monatomic anions have charges equal to the group number minus 8. The oxyanions have even charges for
even-group central atoms and odd charges for odd-group central atoms, but the rule does not give a simple
way to determine the charge definitely for oxyanions as it does for monatomic anions.

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6.14. Name the following ions: (a)Co ,(b)Fe ,(c)Pt , and (d)Hg 2 2+ .
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Ans. (a) Cobalt(III) ion (b) Iron(II) ion (c) Platinum(II) ion (d) Mercury(I) ion
6.15. Which metals in each of the following periodic groups form ions of only one charge: (a) IA, (b) IIA,
(c) IIIA, (d) IB, and (e) IIB?
Ans. (a) All the alkali metals (but not hydrogen) (b) All the alkaline earth metals (c) Aluminum ion
(d) Silver ion (e) Zinc and cadmium ions

6.16. What is the charge on each of the following ions? (a) cyanide, (b) hydroxide, (c) peroxide, (d) nitride,
and (e) chloride.

Ans. (a)1− (b)1− (c)2− (d)3− (e)1−

6.17. Using the periodic table if necessary, write formulas for the following compounds: (a) hydrogen sulfide,
(b) barium chloride, (c) ammonium phosphate, (d) aluminum sulfate, (e) calcium bromide,
(f) lithium sulfide, and (g) sodium fluoride.
Ans. (a)H 2 S(b) BaCl 2 (c) (NH 4 ) 3 PO 4 (d)Al 2 (SO 4 ) 3 (e) CaBr 2 (f)Li 2 S(g) NaF

6.18. Write formulas for copper(I) sulfide and (b) copper(II) sulfide.

Ans. (a)Cu 2 S(b) CuS

6.19. Name the following compounds: (a) AgClO 3 and (b) Al(ClO) 3 .
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Ans. (a) Silver chlorate and (b) aluminum hypochlorite. Note that parentheses enclose the ClO ions, because
there is a subscript to show that there are three of them. In (a), there is only one anion that contains three
oxygen atoms.