You may use your 8.2 notes and the vocab sheet

How do polymers form and what are composites made of?

Science Standard 8.3.c: Students know atoms and molecules form solids by building up repeati ng patt erns, such as the crystal structure of NaCl or long-chain polymers.

Science Standard 8.6.a: Students know that carbon, because of its ability to combine in many ways with itself and other elements, has a central role in the chemistry of living

organisms.

8-3: Polymers & Composites

Anticipatory Set

What do plastics have in common?

water-resistant, lightweight, flexible, comes in many colors

InputProteinamino acidPlasticcomposite

PolymersHydrogen is the most common element that

combines with carbonPlants, Food, plastics, and other living

things are all made up of organic compounds

Input & Modeling

Forming form when chemical bonds link large numbers

of monomers in a repeating pattern.Properties of polymers depend on what

monomers it is made from

Input & Modeling

Polymers and Composites Natural Polymers Cellulose -found in the cell walls of fruits and vegetables. Proteins are polymers formed from smaller molecules called amino acids.

Properties of proteins depend on which amino acids use and what ORDER

Synthetic Polymers The properties of synthetic polymers make them ideal starting materials for

many common objects.

The starting materials for many synthetic polymers come from coal or oil. Plastics are the most common synthetic polymers Use them because:

Long lasting Inexpensive Non-reactive flexible

Input & Modeling

CompositesMany composites include one or more polymers.A composite combines two or more substances in

a new material with different properties.Wood is a natural composite made of cellulose

and lignin. The two polymers are weak by themselves, but they are strong when combined together.

Examples: fiberglass, special metals that are light and strong (planes, fishing poles, tennis rackets)

Input & Modeling

Recycling PlasticsYou can help reduce the amount of plastic

waste by recycling.Plastics do not react very easily with other

substances, so they do not degrade into simpler materials in the environment.

Plastics have increased the volume of trash.

Input & Modeling

Which of the following is a polymer formed from smaller molecules called amino acids?

A. esterB. proteinC. starchD. cellulose

Check forUnderstanding

B

Wood is a natural composite made of two plant polymers, lignin and cellulose. Without cellulose, a tree branch would probably

A. be as hard as steelB. be made of denser wood.C. bend more easily in the

wind.D. snap more easily.

Check forUnderstanding

D

Which of the following statements about synthetic polymers is NOT true?

A. Synthetic polymers last a long time.

B. Synthetic polymers are inexpensive to make.

C. Synthetic polymers react easily with other substances.

D. Synthetic polymers increase the volume of trash.

Check forUnderstanding

C

Either fill out summary2 synthesizeMake an ad for a polymer

to substitute wood. Write the reason it is better.

Guided Practice

Independent Practice8.3 Review/Reinforce.

HOMEWORK CONNECTION Complete the Section 8-3 Review & Reinforce

Write a detailed SUMMARY of the section and complete the UNANSWERED QUESTIONS section of your notes.

Choose two of the remaining Depth & Complexity ICONS in your notes and explain how they relate to this section.