SC100 Class 15 Review Questions 1 Sublimation occurs

SC-100 Class 15 Review Questions • 1. Sublimation occurs when – a. a liquid turns into a solid. – b. an atom accepts electrons when combining with other elements. – c. electrons are transferred from an atom to other elements. – d. a solid turns directly into a gas. – e. a liquid turns directly into a gas.

SC-100 Class 15 Review Questions • 2. Which state of matter maintains a constant volume but not a fixed shape? – a. gas – b. plasma – c. liquid – d. crystal – e. solid

SC-100 Class 15 Review Questions • 3. Sodium Chloride (Na + Cl - ) atoms form a crystal lattice that is held together by – a. hydrogen bonds. – b. salt bonds. – c. covalent bonds. – d. ionic bonds. – e. van der Waals bonds.

SC-100 Class 15 Review Questions • 4. Exothermic and endothermic chemical reactions differ in that – a. energy is given off only in exothermic reactions. – b. energy is given off only in endothermic reactions. – c. the total energy in all involved atoms is the same before and after an exothermic reaction. – d. the total energy in all involved atoms is the same before and after an endothermic reaction. – e. only exothermic reactions can be observed in everyday life.

SC-100 Class 15 Review Questions • 5. Most polymers are characterized as being – a. a collection of small molecules combined into long chains. – b. interesting to study, but having little value in our lives. – c. permanently stable compounds. – d. found in synthetic products, but not in nature. – e. strong and brittle.

SC-100 Class 15 Review Questions • 6. How does the number of electrons in the outer shell determine the chemical characteristics of an element? Determines the kind of bonds that will form; ionic, metallic, or covalent.

SC-100 Class 15 Review Questions • 7. How do you neutralize an acid? Give an example. Add a base (alkali) HCl + Na. OH Na. Cl + H 2 O

SC-100 Class 15 Review Questions • 8. What are three kinds of chemical bonding? Give an example of each. Ionic: Na. Cl Metallic: Copper Covalent: Methane