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Science Materials
| Question | Answer |
|---|---|
| What is a material ? | a material is a substance that can be used to make things, e.g rubber, paper, glass. Different materials are used for difficult purposes depending on their properties. |
| What is a polymer ? | a polymer is a string of many small units,called monomers. |
| What is a co-polymer? | there may be thousands of monomers in a single chain. a chain can also be formed by combining different monomers. in this case the product is called a co-polymers. |
| What are some natural and man-made polymers ? | some natural polymers are wool, cotton, cellulose, hair and silk, and some man-made polymers are PVC, araldite and tefron. |
| What are linear polymers ? | linear polymers are attracted to each other and also tangle together. the attraction between the chains can be overcome by heat, causing the polymers to melt |
| What are cross-links and what effect does it have on a polymer? | some polymers have bands between the chains. cross-links hold the chains in place so they cant untangle even when heated |
| What will result when a few cross-links hold a polymer ? | few cross-links will result in an elastomer |
| What will result when an intermediate amount of cross-links hold a polymer ? | an intermediate amount of cross-links will result in a a flexible solid |
| What will result when a large amount of cross-links hold a polymer ? | a large amount of cross-links will result in a a rigid polymer |
| Do cross-linked polymers melt when heated? | no, they do not melt. but a polymer with no cross links does melt when heated |
| What are five properties of metals? | conducts heat and electricity well, they are strong, malleable, ductile, shiny, can be polished, high melting and boiling point and lose electrons easily to become metal compounds i.e corrodes |
| What is work hardening ? | work hardening makes the metal stronger but more brittle e.g the paper clip |
| What is annealing and what effect does it have on the metal ? | annealing is heating the metal and cooling it slowly which makes the metal softer and easier to shape. |
| What is quenching and what effect does it have on the metal ? | quenching is when a metal is heated and cooled rapidly which makes the metal stronger but more brittle |
| What is tempering and what effect does it have on the metal ? | tempering is when you quench the metal then anneal it which reduces the brittleness of the metal but maintains some of the strength |
| Why do metals corrode to form ionic compounds? | they corrode to form ionic compounds because they lose electrons easily |
| What could you coat a metal to stop it from corroding and getting oxygen reaching it? | paint, oil, plastic, another metal - less reactive e.g chrome or more reactive e.g Zn which resists further corrosive. |
| What is alloying ? | alloying is mixing metals to get an alloy |
| What is thermosetting ? | a substance that set permanently when heated |
| What id thermo plastic ? | a substance that becomes plastic when heated and hardened on cooling and are able to repeat these processes |
Created by:
linda.x
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