Chapter 1 – Practice Problems (Basic Definitions)

Does each statement represent a physical property or a chemical property?

• a. A pile of leaves slowly rots in the backyard.
• b. In the presence of oxygen, hydrogen can interact to make water.
• c. Gold can be stretched into very thin wires.

Does each statement represent a physical change or a chemical change?

• a. Water boils and becomes steam.
• b. Food is converted into usable form by the digestive system.
• c. The alcohol in many thermometers freezes at about −40 degrees Fahrenheit.

Does each statement represent a physical change or a chemical change?

• a. Graphite, a form of elemental carbon, can be turned into diamond, another form of carbon, at very high temperatures and pressures.
• b. The house across the street has been painted a new color.
• c. The elements sodium and chlorine come together to make a new substance called sodium chloride.

Distinguish between an element and a compound. About how many of each are known?

What is the difference between a homogeneous mixture and a heterogeneous mixture?

Identify each as a heterogeneous mixture or a homogeneous mixture.

Identify each as a heterogeneous mixture or a homogeneous mixture.

• a. air
• b. dirt
• c. a television set

In Exercise 8, which choices are also solutions?

In Exercise 9, which choices are also solutions?

Why is iron considered a metal?

Why is oxygen considered a nonmetal?

Distinguish between a metal and a nonmetal.

What properties do semimetals have?

Elemental carbon is a black, dull-looking solid that conducts heat and electricity well. It is very brittle and cannot be made into thin sheets or long wires. Of these properties, how does carbon behave as a metal? How does carbon behave as a nonmetal?

Pure silicon is shiny and silvery but does not conduct electricity or heat well. Of these properties, how does silicon behave as a metal? How does silicon behave as a nonmetal?