Answer Key: Review: Formulas and Mole Problems

1. A cation is a positively charged ion. An example is Ca⁺².
2. The nonmetals are located in the upper right hand area, above the stairstep.
3. Fill in the chart.

   Symbol	Name	# of p+	# of no	# of e-	atomic #	atomic mass
   Al+3	aluminum ion	13	14	10	13	27
   O-2	oxide ion	8	8	10	8	16
   Co+2	cobalt (II) ion	27	32	25	27	59
   F-1	fluoride ion	9	10	10	9	19
   Hg	mercury	80	121	80	80	201

4. a) sodium sulfate   b) dinitrogen tetroxide   c) magnesium chloride   d) potassium dihydrogen phosphate  
   e) silicon tetrafluoride   f) nitrous acid   g) iron (III) nitrate   h) nitrogen dioxide   i) manganese (II) chromate  
   j) cobalt (II) phosphate
5. a) H₂CO₃   b) Ba(ClO₃)₂   c) Sn₃N₄   d) HCl   e) CoH   f) NI₃   g) SCl₆   h) Ag₂CO₃
6. Ionic: a,b,c,d,e,h molecular: f,g
7. atom, molecule, formula unit
8. Br₂, I₂, N₂, Cl₂, H₂, O₂, F₂, At₂
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    so CuO has the highest %Cu (barely)

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19. f) 47.02 g/mole   g) 241.88 g/mol   h) 46.01 g/mol   i) 170.94 g/mol   j) 366.73 g/mol

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