1. Drawing Lewis Structures and predicting formulas of covalent compounds

2.  Atoms bonds to form molecules ◦ Hydrogen and Oxygen bond to form water  We learned that all atoms have electrons but only electrons in their outtermost orbital determine how a bond takes place. ◦ These are called valence electrons

3.  The group number determines how many valence electrons an atom has. ◦ Group 1A = 1 valence electrons ◦ Group 2A = 2 valence electrons… ◦ Group 8A = 8 valence electrons  Only exception is helium which only has 2 valence electrons. ◦ This makes sense since helium only has 2 electrons

5.  All bonds between atoms is due to the sharing or paring of 2 electrons between 2 different atoms ◦ Example H:O  The hydrogen and oxygen bond by 2 electrons.  Octet rule: All atoms want to the Lewis structure of a noble gas, which have 8 valence electrons  Duet rule: Hydrogen on wants 2 electrons to be like helium

6.  How to draw a structure for a compound. Example: H 2 O ◦ Count total amount of valence electrons  H=1x2, O=6X1, 2+6 = 8 ◦ Write the center atom (the first non hydrogen element  O ◦ Using 2 electrons, bond the remaining atoms to the center atom(s)  H:O:H ◦ Using remainder valence electrons, complete the octet rule/duet rules

8.  Double bond = the sharing of 4 electrons between atoms ◦ C::C  Triple bond = sharing of 6 electrons between atoms ◦ C:::C  Lone pair electrons: Two electrons that are on an atom but not bonding that atom to another one.

9.  All compounds need to follow the octet rule. Lone pair electrons can become double and triple bonds to follow this octet rule.

10.  Draw the Lewis structure of CO 2 ◦ Total valence electrons = 4 + 2X6 = 16 ◦ Center atom carbon with 2 oxygen's attached  O:C:O  16-4 = 12 electrons remain ◦ Complete the octet rule for the outer atoms ◦ Now no electrons left so lone pairs need to be shares between bonds

12.  HCN  Total valence = 10  Carbon center atom  Connect outside atoms to center atom ◦ H:C:N ◦ 10-4=6  After putting the remaining 6 electrons around Nitrogen, I need to make a triple bond to complete with octete rule with Carbon  H:C:::N

13.  For polyatomics (multiple atoms) ions, drawing the Lewis structure is the same thing only you add electrons when the charge is negative and subtract electrons when charge is positive.