Chapter 5: Soap

1. Chapter 5: Soap

2. Introductory Activity • Fill a test tube with an inch of water • Add a squirt of cooking oil to the test tube. Observe • Stopper, shake & observe • Add a few drops of soap. Observe • Stopper, shake & observe • With another test tube, add water & soap only. Observe. • Compare the two test tubes.

3. Works based on Determined by Determined by Soap Inter-molecular forces Molecular Geometry Bonding types & Structures

4. Section 5.1—Types of Bonds

5. Why atoms bond • Atoms are most stable when their outer shell of electrons is full • Atoms bond to fill this outer shell • For most atoms, this means having 8 electrons in their valence shell • Called the Octet Rule • Common exceptions are Hydrogen and Helium which can only hold 2 electrons.

6. One way valence shells become full - - - - - - - - - - - - - - Cl Na - - - - - - - - - - - - - - Sodium has 1 electron in it’s valence shell Chlorine has 7 electrons in it’s valence shell Some atoms give electrons away to reveal a full level underneath. Some atoms gain electrons to fill their current valence shell.

7. One way valence shells become full - - - + - - - - - - - - - - - - Cl Na - - - - - - - - - - - - - - The sodium now is a cation (positive charge) and the chlorine is now an anion (negative charge). These opposite charges are now attracted, which is an ionic bond.

8. Ionic Bonding—Metal + Non-metal • Metals have fewer valence electrons and much lower ionization energies (energy needed to remove an electron) than non-metals • Therefore, metals tend to lose their electrons and non-metals gain electrons • Metals become cations (positively charged) • Non-metals become anions (negatively charged) • The cation & anion are attracted because of their charges—forming an ionic bond

9. Bonding between non-metals • When two non-metals bond, neither one loses or gains electrons much more easily than the other one. • Therefore, they share electrons • Non-metals that share electrons evenly form non-polar covalent bonds • Non-metals that share electrons un-evenly form polar covalent bonds

10. Metals • Metals form a pool of electrons that they share together. • The electrons are free to move throughout the structure—like a sea of electrons • Atoms aren’t bonded to specific other atoms, but rather to the network as a whole

11. Bond type affects properties • The type of bonding affects the properties of the substance. • There are always exceptions to these generalizations (especially for very small or very big molecules), but overall the pattern is correct

12. Melting/Boiling Points • Ionic bonds tend to have very high melting/boiling points as it’s hard to pull apart those electrostatic attractions • They’re found as solids under normal conditions • Polar covalent bonds have the next highest melting/boiling points • Most are solids or liquids under normal conditions • Non-polar covalent bonds have lower melting/boiling points • Most are found as liquids or gases

13. Solubility in Water • Ionic & polar covalent compounds tend to be soluble in water • Non-polar & metallic compounds tend to be insoluble

14. Conductivity of Electricity • In order to conduct electricity, charge must be able to move or flow • Metallic bonds have free-moving electrons—they can conduct electricity in solid and liquid state • Ionic bonds have free-floating ions when dissolved in water or in liquid form that allow them conduct electricity • Covalent bonds never have charges free to move and therefore cannot conduct electricity in any situation