4.3 Chemical Properties: (Pages 160-172)

Homework: Pages 165 # 1-3, 5, 7

Investigation 4-B or 4-C

• Key Concepts: (Page 165) • A chemical property of an element or a

compound describes its ability to react with other substances and form new substances.

• Chemical properties of a substance include reactivity with other substances, combustibility, stability, and toxicity.

• Extreme Chemical Reactions

• The chemical properties of peroxide make it useful in hair dye. Nevertheless, there are hazards associated with its use that include skin and eye irritation.

• The ability and toxicity of a substance may influence its impact on the environment. For example, the toxic effects of DDT are made worse by its high stability

• Let's Put it Everywhere• Risks of Pesticides

Reactivity with Other Substances:

1. What is a chemical property?

A chemical property is the ability of a substance to change or react and form a new substance.

2. When does the chemical property of a substance exhibited?

The chemical property of a substance is exhibited during a chemical reaction.

3. In a point form, summarize the 4 reactivities of substances:

Reactivity with water

Reactivity with oxygen

Reactivity with acids

Reactivity with another substance

4. Define combustibility.

Combustibility is the ability of a substance to burn in air.

5. How could the combustibility of a substance influence how the substance is used?

- to avoid accidents/take extra precautions

- to take advantage of the large amount of heat produced by substances that are combustible.

6. Define stability and toxicity. Explain how stability and toxicity can work together to increase the effects of a chemical on the environment.

• Stability is the ability of a substance to remain unchanged.

• Toxicity is the ability of a substance to cause harmful effects.

• The toxic effects of DDT are made worse by its stability. If DDT easily broke down, then it would not bioaccumulate and biomagnify, and its toxic effects on animals and humans would be lower.

7. Which of the following is a chemical property?

a) the smell of a gas

b) the combustibility of propane

c) the freezing point of water

d) the taste of sugar