1. Covalent Bonding Ms. Keller WTHS Chemistry

2. General Covalent-ness Covalent bond- bond that results from the sharing of valence electrons Diatomic molecule: elements that are bonded to itself in nature Br I N Cl H O F

3. General Covalent stuff con’t Types of bonds:  Single = sigma bond  Double = sigma bond + pi bond  Triple = sigma bond + 2 pi bonds  Bonds are electron pairs that are being shared  Lone Pairs- unshared pairs of electrons Lone pair

4. Bond Lengths Bond Length- distance between the nuclei of the 2 atoms that are bonded when they are the most attracted to one another Determined by: ◦ Size of the atoms ◦ How many electron pairs are shared (how many bonds there are)  As # of bonds , the bond length 

5. Energy and Bonds Bond dissociation energy- amount of energy needed to break a specific covalent bond Breaking bonds ALWAYS requires the addition of energy Endothermic vs. Exothermic

6. Naming Binary Molecular Compounds! 1 st element + 2 nd element with the ending -ide Use the following prefixes to indicate the number of the atoms of each element present: 1. mono6. hexa 2. di7. hepta 3. tri8. octa 4. tetra9. nona 5. penta10. deca

7. Naming Acids! Binary method: ◦ 1. prefix = hydro (to represent hydrogen) ◦ 2. root of 2 nd element ◦ Change ending to –ic acid ◦ Ex) HF = hydrofluoric acid

8. Naming Acids! Oxyacids: Acids that contain oxygen Don’t put Hydro in for hydrogen! If the group ends in –ate, it changes to –ic If the group ends in –ite, it changes to –ous ATE –IC, ITE –OUS Throw acid on the end Ex) H 2 SO 4 = Sulfuric Acid Ex) H 2 SO 3 = Sulfurous Acid

9. Let’s Practice Naming… C 2 O 4 NO 2 C 4 H 10 SO 3 N 2 O 5 HCl HBr H 3 PO 4 HClO 2

10. Writing Formulas Just read the name! The prefix tells you how many of each element you have – this is your subscript! ◦ Ex) carbon tetrafluoride = CF 4  Because tetra=4 and it’s attached to fluorine, it becomes the subscript

11. How to Draw Lewis Structures for Covalent Bonding 1. Add up all valence electrons 2. Add up all octets that need to be filled (octet=2 for H) 3. Subtract step 1 from step 2 4. Divide value from step 3 by 2 to get how many bonds are in the molecule Ex) CH 4

12. How to Draw Lewis Structures for Covalent Bonding Some hints for how they fit together: Element closest to the left is usually the central atom Hydrogen is always terminal (on the end)