Questions lecture covers on test 1, 2, 3, 4, 13, 14, 15, 16, 30 Properties of Matter Questions lecture covers on test 1, 2, 3, 4, 13, 14, 15, 16, 30

Intensive Properties-Do NOT change if you change the amount of substance Example: softness, hardness, boiling point, melting point, hair color brown Extensive Properties-Change as you change the amount of a substance: example: mass, volume, length, hair short

Physical Properties of Matter Buoyancy Density Viscosity Hardness Brittleness Elasticity Malleability Conductivity Solubility Tensile Strength

1. Density The “compactness.” It describes how tightly atoms are packed. The relationship of mass to volume Density = mass / volume

Buoyancy The measure of the upward pressure a fluid exerts on an object Buoyant force on an object = mass of the displaced fluid will float if buoyant force > object mass will sink if buoyant force < object mass Shape affects buoyancy: steel rod will sink in water A sheet of steel (like a boat) displaces more water

Buoyancy and Flash Flooding For each foot the water rises up the side of the car, the car displaces 1,500 lbs. of water.  In effect, the car weights 1,500 lbs. less for each foot the water rises. The buoyancy of two feet of water will float most cars, allowing current to carry them away

Viscosity Measure of a material’s resistance to flow Viscous fluids are thick and hard to pour Determined by shape and size of molecules Large, bumpy molecules create more friction as they slide past flow more slowly (MORE VISCOUS) Small, smooth molecules flow more quickly (LESS VISCOUS)

Hardness Measures a solid’s ability to resist scratching Hard substances can scratch softer substances Ex. Diamonds are the hardest natural substance on Earth Does NOT mean rigid!

Brittleness Measures a material’s tendency to shatter on impact (or to break without bending) Ex. Glass shatters in car accidents Now glass is made with a shatter-proof coating that holds the shards together when glass breaks

6. Elasticity Measures a solid’s ability to be stretched and return to its original size Gives objects the ability to bounce and withstand impact without breaking

7. Malleability A solid’s ability to be pounded into thin sheets Metals are very malleable (gold jewelry)

8. Conductivity The ability of a material to conduct: Electric current Heat Sound

9. Tensile Strength A measure of how much pulling, or tension, a material can stand before it breaks Important property of fibers Ex: Spider silk fibers have more than 5 times the tensile strength of steel!

Chemical Properties Reactivity Flammability

Triple Beam Balance Carry from base Estimate the hundreths place 1.23

Graduated Cylinder More precise than a beaker Accuracy-the degree of closeness to the actual value Precision-repeatable; you get the same value each time

Accuracy vs. Precision High __________ low __________ Accuracy

Accuracy vs. Precision High ___________ Low ________ Precision

Why do you think the can of Coke sank and the can of Diet Coke floated? What can you say about the density of the can of Coke compared to the can of Diet Coke? What can you say about the density of the can of Diet Coke compared to water? What is the density of water? How can we calculate the density of the cans of Coke and Diet Coke?

In your journal collect Data Mass of Coke=___________ Volume of Coke=___________ Density of Coke=_______________ Mass of Diet Coke= Volume of Diet Coke= Density of Diet Coke=