2. Chemical Stability Knowing this information about oxidation numbers, which elements are the most chemically stable elements? Noble gases - Are the most stable elements - They have 8 valence electrons and don’t want to gain or lose any electrons

3. Chemical Bonds Only involve ELECTRONS The nucleus does not matter here Elements will not just lose or gain electrons. They will give to another element or take from another element There will always be AT LEAST 2 atoms involved in this process. Binary Compound = Compound with ONLY 2 elements in it NaCl, CaCl 2, K 2 S, etc..

4. Properties of Bonds Remember that when atoms bond, they form new compounds with different properties. The final product has different properties than either of the initial single elements

5. Types of Chemical Bonds There are 3 different ways that two (or more) atoms can interact or BOND 3 types of bonds: Ionic Covalent Metallic

6. Ionic Bonds Formed when one atom gains an electron and another atom loses an electrons. One atom transfers their electrons to the other atom.

7. Ionic Bonds

8. More on Ionic Bonds Occurs between a metal and a nonmetal. Two oppositely charged ions. The product is a neutral compound – and the oxidation #’s add to zero! If they don’t add to zero, you did it wrong.

9. Properties of Ionic Compounds Stronger bonds High melting points Conduct electricity when in solution or in a molten state Generally dissolve in water Generally crystalline solid at room temp.

10. Drawing Ionic Bonds Lets use NaCl (a metal and a nonmetal) 1 st – Determine the oxidation numbers Na = 1+Cl = 1- 2 nd – Draw the Lewis Structure for each atom 3 rd – Draw the electron(s) being transferred in the proper direction DOUBLE CHECK: Does each atom have a full valence orbital?

11. Practice Drawing Ionic Bonds K and Br Mg and Cl K and S

12. Types of Chemical Bonds There are 3 different ways that two (or more) atoms can interact or BOND 3 types of bonds: Ionic Covalent Metallic

13. Covalent Bonds Occur between two nonmetals. Formed when two atoms share electrons with one another. Can be between two different atoms, or between two atoms of the same element Also called Molecular compounds aka MOLECULE

14. Properties of Covalent Bonds Weaker bonds Low melting and boiling points Do NOT conduct electricity when in solution Generally don’t dissolve in water. Many are gases or liquids at room temperature

15. Drawing Covalent Bonds Lets use HCl (2 non-metals) 1 st – Draw the Lewis Structure for each atom 2 nd – Draw the electron(s) being shared 3 rd – Draw each covalent bond as a line between the two atoms DOUBLE CHECK: Does each atom have a full valence orbital?

16. PRACTICE COVALENT BONDS HCl H 2 0 CH 4

17. Diatomic Molecules Two atoms of the same element covalently bonded together. They cannot exist as lone atoms and must bond to something. Called Molecules I Br Cl F O N H BrINClHOF Seven form a seven

18. How do you know which type of bond is formed? IONICCOVALENT - Metal and Nonmetal- Two Non Metals - Transfer Electrons- Share Electrons

19. Bond Types (cont’d) Metallic—Between two metals All metals want to give away electrons because they have + oxidation numbers Don’t transfer electrons specifically Allow electrons to flow from one atom to another. Can pass between many atoms.