Do Now

•How many valence electrons does a sodium atom have? Hint: find this based on sodium’s location on the periodic table.

•How many valence electrons does a nitrogen atom have?

•How many valence electrons does Na3N have? Hint: add three times your answer to question 1 to your answer to question 2.

Aim

•Do we have any other tricks for solving chemical structures?

Introduction

•Draw a Lewis structure of Na3N AND a Lewis structure of AlF3 in the space provided.

•In Na3N, nitrogen is the “central atom.” In AlF3, aluminum is the “central atom.” Based on your structures in question 1, what is meant by central atom?

Introduction•In BCl3, boron is the central atom. You can tell which atom is the central atom by looking at the formula. What is true about the number of the central atom in the three salts you have seen?

•Identify the central atom in each of the following molecules:

A)K2O B) GaH3 C) FrI3

New Idea: Everyone gets a number!Al2O3 Sr3P2

Ion Medley!Fr2S

     

Ra3N2 LiBr

SrCl2     

In2P3 Challenge: NaKCsP

The Last Trick: Multiple Bonds•Q: Do we have a double or triple bond?

•A: If the number of hydrogen + is twice the

number of or less

•Example:

Try it out!Find a structure for C4H8 (bonus points for two):

Find a structure for C2H4O (bonus points for two):

Challenge  Find two structures for C4H6 (there are three):