1. Compounds & Bonds – Unit 5 Why do atoms bond to form compounds? How are bonds formed? How do we represent compounds (names and formulas)?

2. Bonding Essentials Bonds are formed when valence electrons are gained, lost or shared by atoms There are 3 major types of bonds Ionic, Covalent, Metallic Compounds are 2 or more atoms bonded together, with different properties than their elements.

3. Warm-up: What type of bonds are created with: Ionic, Covalent (non-polar or polar) Use the PT (for electronegativity trends) Cr and Fe Rb and Br Cl and Cl H and F Ba and I S and S

4. Covalent Bonds – Strength What is the Relationship between: -Bond energy & Bond length -Bond energy & Number of bonds

5. Intermolecular forces What holds the separate covalent bonds together? http://www.northland.cc.mn.us/favicon.ico

6. Lewis structures: A different way Practice Lewis structures (electron dot) Structural formula (shows bonds with lines) Introduce shape of compounds VSEPR Determine polarity Identify diatomic molecules (7)

7. Electronic cereal: Start with diatomic molecules 2 atoms of the same element (7) Rules to follow: Make every compound 1. Use different colors for each atom 2. Show how each atom contributes electrons to the bond and the lone pairs 3. Determine shape & polarity 1. Polarity is?

8. Properties of Ionic Compounds

9. Properties of Covalent Compounds (molecules) StructureGas, Liquid or “soft” solid HardnessLow Melting pointLow to medium Boiling PointLow to medium Electrical conductivityNo Soluble in waterOnly if polar covalent compound

10. Properties of Metallic Solids StructureSolid HardnessMedium (malleable, ductile) Melting pointMedium to high Boiling pointMedium to high Electrical conductivityYes Soluble in waterNo

11. Opposites Attract Find ions that can bond Write the symbol and the charge Write the new compound formed by combining the ions. Name the compound. Write at least 15 compounds. Ten should include subscripts.

13. Bond type Compound (names & formulas) Properties (physical and chemical)

14. Foldable – Front cover Covalent Bonds form Molecules (Covalent compounds) Ionic Bonds form Ionic Compounds Metallic Bonds form Metallic Solids

15. Page 1 Covalent bond Picture Ionic bond Picture Metallic bond Picture Type of atoms Electrons are: EN difference Type of atoms Electrons are: EN difference Type of atoms Electrons are:

16. Page 2 Molecules (covalent compounds) Lewis structure of water Ionic Compounds (salts) Picture Metallic solid Properties of molecules Properties of Ionic compounds Properties of metallic solids

17. Page 3 Common examples of molecules Common examples of ionic compounds Common examples of metallic solids Names & formulas - Binary molecules - Binary ionic compounds - Brass - Pewter - Sterling silver - Stainless steel

18. Page 4 – names & formulas Molecules Diatomic molecules Acids Ionic Compounds Transition metals Polyatomic ions Metallic solids Bronze Gold

19. Lewis Diagrams Count and add the valence electrons for each atom. Put C as the central atom (or element with with lowest electronegativity). Hydrogen is never the central atom Place 2 electrons for each bond between 2 atoms. Arrange the other electrons evenly around the atoms to satisfy the octet rule. Duet rule for H. If there are not enough electrons, make double or triple bonds.

20. Lewis Diagrams Valence Shell Electron Pair Repulsion VSEPR This means: