Get out your element flash cards and quiz your neighbor for 5 minutes. Element ID Quiz Tomorrow. Be ready for it. Get out your homework from yesterday.
Review – Electron Energy Levels The atom contains energy levels (Bohr called them “shells”) . The first energy level holds 2 electrons. The second energy level holds 8 e- The third energy level holds 8 e-
Example: Helium How many protons: 2 How many neutrons: How many electrons: Electrons in 1st energy level: Electrons in 2nd energy level: Electrons in 3rd energy level: 2 2 2 2
Example: Phosphorus How many protons: 15 How many neutrons: How many electrons: Electrons in 1st energy level: Electrons in 2nd energy level: Electrons in 3rd energy level: 15 16 15 2 8 5
Be Electron Dot Diagram Looks only at the valence electrons. Dots represent electrons. Ex: Beryllium has 2 valence electrons Be
Example: Oxygen: How many valence electrons: O 6
Example: Sodium: How many valence electrons: Na 1
Example: Florine: How many valence electrons: F 7
What do atoms want? A full outer shell. They can get this by getting electrons for giving them away. Ex: Nitrogen has 5 valence electrons. It can gain 3 to get a total of 8 or, It can lose 5 to drop to the lower level Which do you think is more likely?
Examples: Aluminum: How many valence electrons: How many does it need to get: How many can it give away: 3 5 3 Al
Examples: Argon: How many valence electrons: How many does it need to get: How many can it give away: 8 8 Ar
+ Cl Na = Cl Na How do they bond? An atom that needs will get from an atom that gives. Chlorine needs 1 electron and Sodium is happy to give one up. + Cl Na = Cl Na
How about water? Get a whiteboard and lets practice.
Homework Worksheet on Lewis Structures.