1. Atomic Structure & Model
– The Basics

2. I. Atomic Structure
A. Atomic Structure Review

3. II. Bohr Model Electron Energy Shells
Electrons are arranged in shells around the nucleus in predictable locations
The shell closest to the nucleus must fill all seats before seats farther from the nucleus are filled.

4. II. Bohr Model 1 2 electrons 2 8 electrons 3 4 18electrons
Shell Number
Available Seats 1
2 electrons 2
8 electrons 3 4
18electrons

5. II. Bohr Model Atoms are more stable when their outer shell is full.
Atoms that do not have a full outer shell tend to gain or lose electrons. This results in a full outer shell and therefore, stability. This is called the octet rule.
Periodic table periods (aka the rows) share the same number of shells.

6. II. Bohr Model Valence Electrons
Valence Electrons are electrons located on the outmost energy shell of an atom.
They are responsible for creating bonds with other atoms.
Periodic table families (aka the columns) share the same number of valence electrons.

7. II. Bohr Model

8. II. Bohr Model Drawing Bohr Models
Find your element on the periodic table.
Determine the number of electrons (it is the same as the atomic number).
Find which period your element belongs to.
Elements in the 1st period have one energy level
Elements in the 2nd period have two energy levels
Elements in the 3rd period have three energy levels, etc. etc..

9. II. Bohr Model Draw a nucleus with the element symbol inside.
Draw the number of energy shells around the nucleus.
Add the correct number of electrons to each shell.
Remember…
Shell Number
Available Seats 1
2 electrons 2
8 electrons 3 4
18 electrons

10. II. Bohr Model
Check your work! Find what family your element belongs to!
Elements in the 1st family have one valence electron.
Elements in the 2nd family have two valence electrons.
Elements in the 3rd family have three valence electrons, etc., etc..

11. Bohr-ing Practice ;-) For an Atom of Hydrogen: 1 Electron!
Simple, you just draw the first electron
here

12. Bohr-ing Practice ;-) For an Atom of Helium: 2 Electrons!
Simple, you just draw the second electron
here

13. Bohr-ing Practice ;-) For an Atom of Lithium: 3 Electrons!
But wait a minute…We said that only 2 Electrons can fit into the first level
So What do we do when it’s full????

14. Bohr-ing Practice ;-) For an Atom of Lithium: 3 Electrons!
Simple, you just draw the third Electron
here