1. Chapter 4 Formation of Compounds

2. Properties of Salt White solid at room temperature Crystal shaped cubes Hard & brittle Solid salt does not conduct electricity but melted it does Dissolves easily in water & salt water is excellent conductor of electricity

3. Properties of components Sodium Shiny, silvery-white, soft, solid element Metallic Melts at temperatures above 98˚ C High reactivity Chlorine Pale green, poisonous gas with choking odor Slightly soluble in water Non-metal High reactivity

4. Properties of Carbon Dioxide Colorless, odorless, and tasteless gas Soluble in water Water solution is weak conductor of electricity Relatively stable Does not support burning

5. Properties of components Carbon Nonmetal Fairly unreactive at room temperature At higher temperatures is reactive Burns easily Oxygen Nonmetal, colorless, odorless, and tasteless gas Supports burning Slightly soluble in water More reactive than carbon Most abundant element in Earth’s crust

6. Properties of Water Occurs in Earth’s environment in all three states of matter Boils at 100˚C and freezes O ˚C Pure water does not conduct electricity in any state Excellent at dissolving other substances called universal solvent Stable Acts as medium in which chemical reactions occur

7. Properties of components Hydrogen Lightest and most abundant element Nonmetal, odorless, tasteless, and colorless gas Reactive Does not conduct electricity Slightly soluble in water Oxygen Nonmetal, colorless, odorless, and tasteless gas Supports burning Slightly soluble in water More reactive than carbon Most abundant element in Earth’s crust

8. Atoms become stable by having eight electrons in their outer energy level (or two electrons in the case of some of the smallest atoms)

9. Ways to Achieve a Stable Outer Energy Level

10. Properties Ionic Compounds  Form strong, three- dimensional crystal structure  Crystalline solids at room temperature  Hard, rough, and brittle  Attractions between ions are strong  Dissolve in water  Conduct electricity in liquid state Covalent Compounds  Composed of molecules  Liquids or gases at room temperature  Do not conduct electricity in the pure state  Do not dissolve in water  Usually less soluble in water than ionic compounds