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# End Of Chapter Exercises

## Composition of matter

Exercise 12.1

Give one word or term for each of the following descriptions.

1. A composition of two or more atoms that act as a unit.

2. Chemical formula that gives the relative number of atoms of each element that are in a molecule.

Solution not yet available

Give a definition for each of the following terms:

1. molecule

2. ionic compound

3. covalent network structure

4. empirical formula

5. ball-and-stick model

Solution not yet available

Ammonia, an ingredient in household cleaners, is made up of one part nitrogen ($$\text{N}$$) and three parts hydrogen ($$\text{H}$$). Answer the following questions:

1. is ammonia a covalent, ionic or metallic substance?

2. write down the molecular formula for ammonia

3. draw a ball-and-stick diagram

4. draw a space-filling diagram

Solution not yet available

In each of the following, say whether the chemical substance is made up of covalent, molecular structures, covalent network structures, ionic network structures or metallic structures:

1. ammonia gas ($$\text{NH}_{3}$$)

2. zinc metal ($$\text{Zn}$$)

3. graphite ($$\text{C}$$)

4. nitric acid ($$\text{HNO}_{3}$$)

5. potassium bromide ($$\text{KBr}$$)

Solution not yet available

Refer to the diagram below and then answer the questions that follow:

1. Identify the molecule.

2. Write the molecular formula for the molecule.

3. Is the molecule a covalent, ionic or metallic substance? Explain.

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Represent each of the following molecules using its chemical formula, structural formula and the ball-and-stick model.

1. nitrogen

2. carbon dioxide

3. methane

4. argon

Solution not yet available