Concept Summary Batesville High School Science
Crystals Crystals are regular geometrical arrangements of atoms. Most metals have a regular crystalline structure. Many minerals are crystals.
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.
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
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
Weight Density Weight density is often used to compare liquids. Weight density = weight/volume
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
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
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.
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.
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
The End