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KEY-FinalExamStudyGuide_Fall2013

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Name ___________________________ Date ___________________ Class __________________<br />

CHAPTER 7, Ionic and Metallic Bonding (continued)<br />

4. Why do beryllium and fluorine combine in a 1 : 2 ratio?<br />

They combine in a 1 : 2 ratio because each beryllium atom gives up two electrons, but<br />

each fluorine atom only accepts one electron. Therefore, two fluorine atoms are<br />

needed to react with each beryllium atom.<br />

5. A chemical formula shows the types and ______________________ numbers of atoms in<br />

the smallest representative unit of a substance.<br />

6. List the numbers and types of atoms represented by these chemical formulas.<br />

a. Fe 2 O 3 _____________________________________________________________________<br />

2 atoms of iron, 3 atoms of oxygen<br />

b. KMnO 4 ___________________________________________________________________<br />

1 atom of potassium, 1 atom of manganese, 4 atoms of oxygen<br />

c. CH 3 ______________________________________________________________________<br />

1 atom of carbon, 4 atoms of hydrogen<br />

d. NH 4 NO 3 __________________________________________________________________<br />

2 atoms of nitrogen, 4 atoms of hydrogen, 3 atoms of oxygen<br />

7. What is a formula unit?<br />

A formula unit is the lowest whole-number ratio of ions in an ionic compound.<br />

8. Explain why the ratio of magnesium ions to chloride ions in MgCl 2 is 1 : 2.<br />

There must be twice as many chloride ions (Cl – ) to balance the magnesium<br />

ions (Mg 2+ ) to form an electrically neutral compound.<br />

9. Describe the structure of ionic compounds.<br />

Ionic compounds exist as collections of positively and negatively charged ions<br />

arranged in repeating three-dimensional patterns.<br />

Properties of Ionic Compounds (pages 196–198)<br />

10. Most ionic compounds are _____________________________ crystalline solids at room<br />

temperature.<br />

11. Is the following sentence true or false? Ionic compounds generally have low<br />

melting points. _________________<br />

false<br />

12. What does a coordination number tell you?<br />

It is the number of ions of opposite charge that surround an ion in a crystal.<br />

13. What is the coordination number of the ions in a crystal of NaCl? _________________ 6<br />

© Pearson Education, Inc., publishing as Pearson Prentice Hall. All rights reserved.<br />

62 Guided Reading and Study Workbook

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