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EQ#6 What are the properties of matter? . What is a (Pure) Substance?. A substance is matter that is uniform & has an unchanging composition. A formula can be written for a substance Ex. H 2 0 or 0 2 A substance can be either an element or a compound . . Elements and Compounds. - PowerPoint PPT Presentation
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EQ#6 What are the properties of matter?
What is a (Pure) Substance?
• A substance is matter that is uniform & has an unchanging composition.
• A formula can be written for a substance –Ex. H20 or 02
• A substance can be either an element or a compound.
Elements and Compounds• Element:
– Contains only 1 type of atom– Found on the Periodic Table
• Ex. O2, Fe, Na, He
• Compound:– 2 or more elements chemically
combined– Ex. H2O, C6H12O6, CO2
Physical Properties
• These are characteristics that can be observed without changing the sample’s composition.
• They are observed directly with the senses.
• Examples include: – Shape, color, density, odor, boiling
point, etc.
What are some physical properties of water?
Chemical Properties• This is the ability of a substance to
combine with other substances or change into 1 or more substances.
• It is the result of contact with another substance, or due to the application of thermal or electrical energy.
Examples of Chemical Properties:
• Iron rusts when combined with oxygen
• Water decomposes into hydrogen & oxygen
• Magnesium burns
Quiz: Physical or Chemical Property?
• Water boils at 100°C.• Silver tarnishes.• Propane burns.• Density of Al is 2.7 g/mL.• Carbon is black & brittle.• Zinc reacts in acid.
Extensive vs. Intensive Properties
• Extensive properties:– Depends on the amount of a substance
present.– Ex. Mass, volume, length
• Intensive properties:– Independent of the amount of substance
present.– Ex. Density, boiling point, reactivity
Phases of MatterPhase Definite
Shape?DefiniteVolume
DistanceBetweenParticles
Ex.
Solid Yes Yes TightlyPacked
Ice, wood
Liquid No Yes Less Close
Water,mercury
Gas No No Far apart Air, H2O vapor
• Vapor is a gaseous state of substance that is normally a solid or liquid at room temperature.
Phases (States) of Matter
Physical Changes: • Physical changes are changes that occur
without changing the composition of the substances.
• Bending, grinding, crushing, dissolving, cutting, phase changes etc.
Physical Change Examples:• Ice melting:
H2O (s) H2O (l)
• Potassium permanganate dissolving in water:
Chemical Changes:• Chemical changes are changes that
occur when substances change into new substances.
• Also called a chemical reaction.
• Exploding, rusting, oxidizing, burning, etc.
• New substances formed have a different composition & different properties.
Indicators of a Chemical Reaction:
1. Gas formation2. Solid formation
(precipitate)3. Change in color4. Change in odor5. Change in
temperature
Precipitate:
Physical or Chemical Change?
• Alcohol evaporating.• Iron rusting.• Dynamite exploding.• Sugar dissolving in water.• Water boiling.• Baking soda & vinegar
reacting.• Dry ice subliming.