Diamonds vs. Spider Silk Crystals and Polymers
Do you remember which molecules represent a solid? • The molecules of most solids form regular shapes through repeating patterns.
Two Types of Solids Crystals (Diamonds) Polymers (Spider web silk)
Crystalline Solids • Crystals (crystalline solids) have molecules that form a regular, repeating pattern. • These patterns create crystals. • In general, crystalline solids do not get soft when heated. • Examples of crystalline solids are sugar, salt, and diamonds.
The Molecules in Crystalline Solids Diamonds Graphite (pencil lead) • What do the round structures represent? • Why are all the atoms the same color? • Which substance is more hard? Why?
Diamond vs. Graphite What is similar about these substances? Both diamonds and graphite are made of the same atoms, carbon; despite having distinct physical properties. • What accounts for their different physical properties (hardness, luster, density, etc)?
Two Models of Salt Molecules • What kind of observations can you make about the molecular structure of salt? There are 2 different types of atoms arranged in repeating patterns that can’t change position.
Polymers • A polymer is a large, repetitive, string-like molecule. • Most organic structures are polymers made of Carbon, Hydrogen, Oxygen, and/or Nitrogen.
The Molecules in Polymers What are some characteristics of these structures? Cotton Silk
Cotton and Silk • What are some similarities between cotton and silk? • Where do all polymers come from? Polymers come from organic (living or once-living) things like plants, petroleum, and animals.