Ch 5-1 review and 5-2

1. Ch 5-1 review and 5-2 Physical Sci

2. Which are compounds which are mixtures • SO2 • Air in a scuba tank • Distilled water • Oxygen gas • Carbon monoxide

3. Structure of compounds • Three different types • Network of bonded atoms • Bonded positive and negative ions • Separate molecules weakly attracted to each other

4. Structure properties • Network of bonded atoms • Very strong solids • Takes a lot of energy to break the bonds • Very high melting and boiling points • Salt (NaCl) • Sand (SiO2) • Magnesium Fluoride (MgF2)

5. Some compounds are made of separate molecules weakly attracted to each other • The atoms within the molecule are strongly bonded together but they are not greatly attracted to other molecules • Low boiling points • Low melting points (can be solid but often liquid or gas at room temperature)

6. Hydrogen bonds • Water molecules (and other polar molecules containing hydrogen) are polar • Polar means they have a negative end and a positive end • The hydrogen bond is not as strong as the bonds that make a water molecule

7. Review Questions • Why does AgI have a higher melting point than vanillin (a compound used for flavoring) C8H8O3 • Which molecules have a greater attraction for each other, C3H8O rubbing alcohol, or CH4 molecules of methane gas • O-H bonds in water are 95.8 pm long while S-H bonds in dihydrogen sulfide are 135 pm. Why are S-H bonds longer?

8. 5-2 Ionic and Covalent Bonds • Three types of bonds exist • Ionic • Metallic • Covalent • Why do atoms bond • To obtain a full outer shell of electrons (stable electron configuration) • When do atoms bond • When valence electrons interact

9. What is a bond • Bonds are somewhat flexible • Think of them like stiff springs, they can bend, vibrate, move slightly back and forth • Bonds hold atoms together

10. Electron configuration • Bonding example 2 H come together to form H2 • One valance electron (wants 2) so it shares with another hydrogen

11. Ionic bonds • Form between oppositely charged ions • Metals bonding to nonmetals • Electrons are lost by one atom and gained by another atom to achieve stable electron configuration • Result is positive ion and negative ion • Opposites attract and from ionic bond

12. Ionic Bonds cont. • Sodium ion Na+ • Chlorine ion Cl- • Ionic bond NaCl • Net zero charge • Ionic bonds form networks • One salt molecule • But due to charges they form a network

13. Ionic bonds conduct electricity • Solid ionic compounds do not conduct electricity because the ions are locked in place • But if they are dissolved in water or melted they will conduct electricity!