1. Atomic Theory

2. The periodic table and atomic theory
6.2
The periodic table and atomic theory

3. Things to know Atomic number = number of protons (He = 2)
= number of electrons (He = 2)
Electrons=protons only and onllllllly in a neutral atom. How do you know it’s neutral? It does NOT have any ion charge!!!
Atomic mass = number of protons + number of neutrons
4 =

4. Name
Atomic mass
Number of protons
(Atomic number)
Number of electrons
Number of neutrons K V Cl

5. So let’s talk about location now!
So we know how many protons, electrons and neutrons each atom has….
Well, where do we find them? Can we draw them? p+ n e

6. Bohr Diagrams
Bohr models show electron arrangement in shells

7. Drawing Bohr Diagrams
Bohr diagrams map out the number of protons, neutrons, and electrons in an atom.
Step 1: Draw the nucleus with the number of protons and neutrons
Step 2: Draw the electrons in their shells
1st shell fills with 2 electrons
2nd shell fills with 8 electrons
3rd shell fills with 8 electrons
4th shell fills with 18 electrons K
p= 19
n=20 K
p= 19
n=20
The outside shell is called the valence shell
The electrons in the valence shell are called valence electrons

8. Together: Draw the Bohr diagram for the following

9. Try: Draw the Bohr diagram for the following

10. Bohr Model Patterns
See page 66
Chemical families on the periodic table have the same number of valence electrons
Elements in the same period have the same number of shells
Period number indicates the number of electron shells

11. Valence Electrons: Total number of electrons in the most outer shells that can participate in a chemical bond.
Atom
Group K I Ca 2 Ga 13 Ge 14 As 15 Se 16 Br 17 Kr 18
# of valence e-

12. Atoms like to be as stable as possible
All the elements on the periodic table are neutral atoms. Meaning, they have not gained or lost any electrons.
However, all these elements tend to lose or gain electrons to become as stable as possible!
When neutral atoms lose or gain electrons, they become _____________

13. So how do atoms become stable?
Let us take a look at the noble gases
Noble gases are very unreactive because their atoms have _______ valence shells.
Filled shells make atoms __________
Filled means the atom has 2,8, or 18 electrons in the valence shell!
But atoms with unfilled shells tend to lose or gain electrons to become filled.

14. Atom Stability
Atoms, other than the noble gases, gain or lose electrons in order to achieve the stability of noble gases. Gaining or losing electrons makes atoms into ions.

15. To gain or to lose, that is the question!
If an atom has 1,2,3 electrons in the valence shell, it will tend to _____ electrons to become stable. If an atom has 4,5,6,7 electrons in the valence shell, it will tend to ______ electrons to become stable. If an atom has 8 electrons? Wellllll…it’s already stable!!!  unreactive! Like all the noble gases.

16. ION CHARGES
When an atom loses electrons, it gets a positive charge. It becomes a positive ion. Ca When an atom gains electrons, it gets a negative charge. It becomes a negative ion. O

17. What is the ion charge for?
N Be

18. Atom Stability Metals lose electrons to form positive ions
Non-metals gain electrons to form negative ions
Ions have a similar electron arrangement to the nearest noble gas
There is a nice trend on the periodic table to help you out  let’s see what it is!

19. How to figure out ion charges using the periodic table

20. Give the ion charges for the following
Ca Br O Na

21. 6.3 chemical families
Page 158

22. Homework
6.2 Page 156 1,2,3,4 6.3 Page 161 9,10

23. Chapter 6 review
Page 166
1,2,3,7,9,12,13