1/11/12 A/B DayLEQ: What is the difference between a physicaland chemical change and how can we tell whenthey happen?1. What is the difference between a mixture and asolution?2. In a glass of chocolate milk, what is the solvent andwhat is the solute?3. What does solubility measure?4. A scientist needs to use a material that will not getvery hot. Should the scientist use something with aHIGH specific heat or a low specific heat?5. EXPLAIN your answer to #4!
Let’s Review:If each of thesematerials isexposed to thesame amount ofheat, which onewill be theCOOLEST?
HOT Q: If 5 grams of gold melts at200° C, what temperature will cause50 grams of gold to melt?
HOT Q: Which pure substance iscomposed of more that oneelement? a.Carbon b.Gold c.Water d.Sodium
Help a Scientist pick the right element:1. A metal2. A nonmetal3. A metalloid4. Something malleable5. Something ductile6. Something that is magnetic7. Something that will conduct heat8. Something that will block heat9. Something that is a semiconductor
FIND THAT ELEMENT!1. GROUP 1, PERIOD 1 =2. GROUP 6, PERIOD 7 =3. GROUP 2, PERIOD 5 =4. GROUP 9, PERIOD 4 =5. GROUP 17, PERIOD 3 =6. GROUP 11, PERIOD 4 =
EOG Question:How can a scientist, using the periodictable, find an element with properties similar toanother element? a) by comparing density b) by finding its periodic group c) by comparing malleability d) by comparing atomic weight
CHEMICAL WEATHERING:• Chemicals break down rock by chemically changing the rock• Usually indicated by color change!• Example: Acid Rain, rust
MECHANICAL WEATHERING:• Physical changes to rock(rocks break into smaller pieces)• Example: ice, salt, wind, and water break down rocks
Today’s LEQ: What is the difference between a physical and chemical change and how can we tell when they happen?By the end of today, you should be able to…1. Describe the difference between an physical and chemical change.2. Use observable evidence to decide if a change is chemical or physical
FOCUS VOCABULARY:87. Chemical Change88. Physical Change
Draw this in your notes: Changing SubstancesPhysical Change: Chemical Change:changes the physical substance is changedtraits of a into a new substancesubstance, NOT the (changes the identityidentity of the of something)substance Ex. Burning Paper!
Chemical Change: Burning paper PaperBurnt Paper is a DIFFERENT SUBSTANCE!
Instructions:I give you: 8 different types of evidencethat happen during physical and chemicalchangesYou: use your brain to decide which ofthe things is evidence of physical changeand which of the things is evidence ofchemical change
Physical Chemical -Changes color -Melting, freezing, or boilingEVIDENCE -Burst of heat -Change in mass or volume -Smoke forms -Change in shape -Usually reversible -Usually irreversible
Physical Change: Chemical Change:Evidence: Evidence:1. Melting, freezing, or 1. Changes colorboiling 2. Burst of heat2. Change in mass orvolume 3. Smoke forms3. Change in shape4. Usually reversible 4. Usually irreversible
What evidence can we use to tell this is a physical change? Paper
What evidence can we use to tell this is a chemical change? PaperBurnt Paper is a DIFFERENT SUBSTANCE!
HOT Q: How do physical and chemical changes relate to thedifferent ways that the surface of the earth changes over time??
Key Points:1. A _________ changes the physical characteristics of a substance.2. A __________ changes something into a new substance.3. Changing color is evidence of a ___________.4. Changing phases or states of matter is evidence of a __________________.
Summarizer:1. What is the difference between a chemical change and physical change?2. Is melting copper an example of a physical or chemical change?3. How can you tell the answer to #2?4. Is a rusting nail an example of a physical or chemical change?5. How can you tell the answer to #4?