1. Concept Summary Batesville High School Science

2. Crystals  Crystals are regular geometrical arrangements of atoms.  Most metals have a regular crystalline structure.  Many minerals are crystals.

3. Size of Crystals  Many crystal structures are evident to the naked eye.  Quartz, copper sulfate, galvanized tin, etc.  Many crystals can be seen only under a microscope.  NaCl, etc.  Many sub-microscopic crystals are revealed by x-ray diffraction.

4. Density  Density measures how much matter is packed into a unit space.  Density depends on the masses of the atoms and how closely they are packed together.  Density = Mass/Volume

5. Density  Density of liquid water = 1.00 g/cm 3  Density of water ice = 0.92 g/cm 3  Densest material on Earth is osmium  Density of osmium = 22.6 g/cm 3

6. Weight Density  Weight density is often used to compare liquids.  Weight density = weight/volume

7. Specific Gravity  Specific gravity is another measure of density.  Specific gravity =  Since density of water = 1.00 g/cm3, specific gravity = numerical density Density of the substance Density of water

8. Elasticity  When a substance returns to its original shape after being deformed, it is elastic.  If an elastic material is stretched beyond its elastic limit, it will remain permanently deformed.  Stretch is proportional to force  Hooke’s Law: F = kx

9. Compression & Tension  Compression is squeezing.  Tension is stretching.  Beams can be both under tension and compression at the same time.  Top under tension, bottom under compression, or vice versa.  I-beams.

10. Scaling  Scaling studies how size affects, weight, strength, and surface area.  Strength is proportional to cross-section area  Heat transfer is proportional to surface area.  Weight is proportional to volume.  Food requirement is proportional to volume.

11. Scaling  Double each side of a cube.  It has 4 (= 2 2 ) times the cross section 4 times the strength  It has 4 (= 2 2 ) times the surface area 4 times the heat loss/gain  It has 8 (= 2 3 ) times the volume 8 times the weight Needs 8 times the nutrients

12. The End