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Physical versus Chemical Properties & Changes. Chapter 1 – Section 3 Changes in Matter. Reviewing MATTER. Matter: anything that has mass and takes up space Mass – the amount of matter in something Volume – the amount of space something occupies Which of the following is matter? A car?
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Physical versus Chemical Properties & Changes Chapter 1 – Section 3 Changes in Matter
Reviewing MATTER • Matter: anything that has mass and takes up space • Mass – the amount of matter in something • Volume – the amount of space something occupies • Which of the following is matter? • A car? • A box? • You?
What is a property? • CHARACTERISTIC PROPERTY: A characteristic of a substance that can be observed and/or measured
What are characteristic properties good for? • We can use these properties to identify substances. • 2 basic types of properties of matter: PHYSICAL and CHEMICAL • ALWAYS the same whether object is large or small
Physical Property PHYSICAL PROPERTY: A property that can be observed WITHOUT CHANGING the identity of the substance. A feature of a substance that does NOT involve a chemical change. Same substance, same compounds you started with.
Physical Property • Examples: • * Color • * Shape • * Hardness • * Density • * Texture • * State @ room temp (solid, liquid, gas) • * Size (mass, volume) • * Melting point • * Boiling point * Malleability (hammer into sheets) * Ductility (stretch into wires) * Taste (don’t taste unknown chemicals!) * Odor (don’t sniff unknown chemicals!) * Luster (surface appearance)– shiny, dull * Solubility (ability to dissolve in a substance) * Electrical conductivity * Thermal conductivity (heat) * Sound conductivity
Chemical Property CHEMICAL PROPERTY: • A property that can only be observed by CHANGING the identity of the substance. • Characteristics that indicate if a material can undergo a certain chemical change. • A property of matter that describes its ability to be involved in chemical reactions. • Chemical properties can ONLY be observed AS the substances are changing into different substances.
Chemical Property Examples: * Flammability (Combustibility)– ability to burn * Ability to rust from oxygen * Reactivity with water or vinegar * Toxicity- how dangerous the material is * Radioactivity- does the material give off radiation * Sensitivity to light- how sensitive the material is when placed under a light or the sun
Physical changes are those changes thatDO NOTresult in the production of a new substance.If you melt a block of ice (frozen H2O), you still have H2O at the end of the change. Physical Changes
If you break a bottle, you still have glass. Painting your nails will not stop them from being fingernails. Some common examples of physical changes are: melting, freezing, condensing, breaking, crushing, cutting, and bending. Physical Changes
Affects one or more physical properties of a substance, but not chemical properties or identity of a substance (appearance affected, but not composition) Physical Changes
Some, but not all physical changes can be reversed. You could refreeze the water into ice, but you cannot put your hair back together if you don’t like your haircut! Physical Changes
Chemical Changes • Chemical changes, or chemical reactions, are changes that result in the production of another substance. • Occurs when 1 or more substances change into entirely new substances with different characteristic properties. • Cannot reverse chemical changes using physical means, sometimes cannot reverse at all
Common examples of chemical changes that you may be somewhat familiar with are: digestion, respiration, photosynthesis, burning, and decomposition. Chemical Changes
FLAMMABILITY: A material’s ability to BURN in the presence of OXYGEN Chemical Changes
When you burn a log in a fireplace, you are carrying out achemical reactionthat releases carbon. When you light a candle at home, you are carrying out a chemical reaction that produces carbon (soot) and carbon dioxide gas. Chemical Changes
REACTIVITY:How readily (easily) a substance combines chemically with other substances. Chemical Changes
Clues to Chemical Changes Dramatic color change (can’t use this alone!)Fizzing, foaming (new production of gas)Precipitate (new production of solid substance)Production or use of energy (light, heat)Production of sound, odor
Physical or Chemical Change? QUIZ TIME
Physical or Chemical Change? • Painting Wood • PHYSICAL
Physical or Chemical Change? • Digestion of food • CHEMICAL
Physical or Chemical Change? • Sugar dissolving in water • PHYSICAL
Physical or Chemical Change? • Iron turning red when heated • PHYSICAL
Physical or Chemical Change? • Evaporation • PHYSICAL
Physical or Chemical Change? • A pond freezing in winter • PHYSICAL
Physical or Chemical Change? • Melting ice • PHYSICAL
Physical or Chemical Change? • Cutting wire • PHYSICAL
Physical or Chemical Change? • Painting fingernails • PHYSICAL
Physical or Chemical Change? • Cutting fabric • PHYSICAL
Physical or Chemical Change? • Baking muffins • CHEMICAL
Physical or Chemical Change? • Shattering glass • PHYSICAL
Physical or Chemical Change? • Decomposition of old leaves • CHEMICAL
Physical or Chemical Change? • Wrinkling a shirt • PHYSICAL
Physical or Chemical Change? • An old nail rusting • CHEMICAL
Physical or Chemical Change? • Burning Paper • CHEMICAL