Physical and Chemical Changes

1. Physical and Chemical Changes

2. 6th grade Review —    Atoms are the smallest particles from which elements are made. —    Molecules are two or more atoms bonded together to form a substance that exists on its own and keeps it properties.—    Compoundscontain atoms from two or more elements chemically bonded to form a new and different substance.—Organic compounds are made up of carbon atoms bonded to atoms of other elements.

3. What is an element? An element is a pure substance that cannot be broken down into simpler substances. It contains only one type of atom. • Why isn’t sodium chloride listed on the periodic table?It’s a compound. Only elements are listed on the table. • What is a compound? A compound is a substance made by chemically combining two or more elements to form a new and different substance, and the bond cannot be broken by physical means. • Is O2 a compound?  No, because it is made up of only one element. It is considered a molecule because it is two atoms of the same element.

4. An organic compound is made up carbon atoms bonded to atoms of other elements. Examples are carbohydrates, proteins, lipids, and nucleic acids. • if one element is added to the chemical makeup of a substance, the substance changes into a new and different substance.

5. Cellular respiration is the process that cells use to break sugars (glucose) into a form that the cells can use for energy. This process occurs in plants and animals. Cellular respiration takes food in the form of sugar or starch.

6. Which of the substances in the cellular respiration equation are compounds? (CO2, H2O, C6H1206) • Which of the substances are molecules? (O2) • Which elements compose carbon dioxide? (Carbon and oxygen)

7. Decoding Atom Informationfrom the Periodic Table (copy this!) Atomic number # of protons = # of electrons 6 C Carbon 12.0 Atomic mass = # of protons plus the # of neutrons

8. How are Elements Classified? • Three Regions - metals, and nonmetals, and metalloids

9. Metals • Metals - include group 1 -12 and some elements from 13 -16 - most known elements - good conductors of electricity/heat - solid at room temperature, except mercury ex. Na, Ag, Pb

10. Non Metals • Definition - elements that are poor conductors of electricity/heat - low boiling points, SO…most are gases at room temperature - varying chemicalproperties ex. He, F, P

11. Metalloids • Definition - elements with properties that fall between those of metals and non metals - chemical properties will vary, usually most like the region they are closer to ex. As: closer to non metal most of it’s property will resemble that

12. In digestion… physical and chemical changes (these are all test facts) • Physical change is digestion is represnted by teeth chewing. • Substances in the mouth and stomach that break down fats and proteins represent chemical change in food for the digestive process. • Saliva, stomach acid, bile and pancreatic juices are the chemical substances that help with the digestive process.

13. Physical and Chemical Changes in Digestion • Thermal energy is a form of energy. The process of the movement of thermal energy produces heat. Digestion involves physical and chemical changes. During chemical changes, food is broken down and releases thermal energy. The movement of the thermal energy through the body is heat.

14. More test facts • The digestive systems main function is to breakdown large molecules into smaller ones. • Carbohydrates can be broken down to sugars.

15. Test questions • What energy transformation is taking place when an animal eats food to keep warm? Chemical to thermal What type of energy conversion is going on in the body as energy from food is turned into fat? Chemical to chemical