1. Covalent Bonds Due 11/21/13 http://tinyurl.com/mp7wlpw

2. Objectives Draw the structure for covalent compounds using the NASL method or the conceptual method Show ALL work for ALL examples!

3. Covalent Bonds 2 Nonmetals Atoms have equal electron affinity, therefore one atom is unlikely to accept an electron from another High ionization energy so atoms are unlikely to lose electrons Atoms are bonded by a pair of electrons shared between them Represented by a pair of dots (electrons) between two Lewis symbols

4. N.A.S.L. Method – Step 1 Example: Carbon Tetrachloride - CCl 1. Place the least electronegative atom in the center (never hydrogen)

5. N.A.S.L. Method – Step 2 2. Needed – Sum of the electrons needed for each atom to achieve its octet. N = 8 for representative elements with the exception of H-2, He-2, Be-4, B-6

6. N.A.S.L. Method – Step 3 3. Available – Add the number of valence electrons from each atom.

7. N.A.S.L. Method – Step 4 4. Shared – Needed – Available. To determine the number of bonds, divide the number of shared electrons by 2.

8. N.A.S.L. Method – Step 5 5. Lone Pair Electrons – Available - Shared. Divide this number by 2 to get the number of lone pairs and distribute between appropriate terminal atoms to fulfill each atom’s octet

9. Conceptual Method 4A5A6A7AHydrogen Common Elements C, SiN, P, AsO, SF, Cl, Br, IH # Bonds # Lone pairs Options

10. Practice 1 Carbon Dioxide – CO 2

11. Practice 2 Ammonia – NH 3

12. Questions?