2.2 PROPERTIES OF MATTERI can:
- classify matter by its chemical and/or physical properties (e.g. color solubility, odor, hardness, density, melting point, and boiling point, viscosity and malleability)
- recall differences of physical and chemical properties
STEEL IS A MIXTURE OF IRON, OTHER METALLIC ELEMENTS, AND CARBON
PHYSICAL PROPERTIES
• Any characteristic of a material that you can observe without changing the identity of the substances that make up the material is a physical property.• Examples of physical properties are color, shape, size, density, melting point, and boiling point.
Appearance
How would you describe a tennis ball?• shape, color, and state of matter. physical properties- diameter, mass,
etc.
Behavior
Some physical properties describe the behavior of a material or a substance.
• Attraction to a magnet is a physical property of the substance iron. (magnetism)
• The ability to flow is another (water vs. molasses)
PHYSICAL PROPERTIES DESCRIBE MATTER
• Help ID a substance• Senses: shape, color, odor, texture
• Some can be measured• Melting point• Boiling point
• Physical properties typically remain constant.• Pure water is always a colorless liquid, never powdery green solid.
• Observable physical property= STATE of that matter.
DENSITY IS A PHYSICAL PROPERTY
• The ratio of the mass of a substance to volume of a substance.
• Why do hot air balloons float?
• Why do stones sink?
• Brick v. sponge?
• D=m/V• Desity=mass/volume
GOLF BALL V. PING PONG
• Both have similar volume.
• Golf ball: 45.9g
• Ping pong ball: 2.5g
• Golf ball has more mass per unit volumn.
PRACTICE
• If 10.0 cm3 of ice has a mass of 9.17 g, what is the density of the ice?
• List the given and the unknown values• M=9.17 g• V= 10.0 cm3
• D= ?
• Plug them in• D= 9.17g/ 10.0 cm3
• D= 0.917 g/cm3
PHYSICAL PROPERTIES HELP DETERMINE USES
• How to you tell if your socks are clean?• odor
• Whether or not your homework will fit in your bag?• Volume
• If your shirt matches your pants?• Color
• Is copper good for electricity?• Conductor
• Will antifreeze remain in liquid form in low or high temps?• Boiling/freezing point of ethylene glycol
EXAMPLES OF CHEMICAL PROPERTIESSodium=reacts very fast (found as compounds)
Gold= much less reactive (found uncombined)
Magnesium= very reactive (emergency flares)
Argon= not reactive (light bulbs last longer)
CHEMICAL PROPERTIES DESCRIBE HOW A SUBSTANCE
REACTS.• Problem= iron reacts with oxygen. What does this cause?
• Solution: paint prevents steel from coming in contact with oxygen.
• Other chemical properties:• Reactivity: the ability of a substance to combine chemically with another.• Flammability: the ability of a substance to react in the presence of oxygen
and burn when exposed to a flame.• Burning wood creates new substance… ash• Gold has chemical property of nonflammable.
COMPARING PHYSICAL AND CHEMICAL PROPERTIES