1. Ionic and Metallic Bonding
Mr. Bostrom
West Forsyth High School

2. Why do atoms bond?
To answer this question we must first look at the elements:
Do we normally find matter in its elemental form?
No – why?
Most atoms are unstable!!!!!!!!
Why?

3. Let’s look at a stable element!
What makes Ne stable?
Valence Electrons – it has a complete set!!!!

4. Back to the original question
Atoms form bonds in order to increase stability!!!!!!!!!!
Example: H2O

5. Another Example
NaCl or Salt

6. Atoms bond together to increase stability!!!
There are three types of bonds
Ionic Bond
Covalent Bond
Metallic Bond
We are going to concentrate on Ionic and Metallic Bonds today

7. What is an Ionic Bond? Na :Cl:  NaCl . . ..
An ionic bond is formed between oppositely charged atoms in which one atom transfer(s) electrons to the other
Na :Cl:  NaCl
- Formed between a metal and a non-
metal . . ..

8. What changes about the atom
The atom that loses electrons gains a positive charge
Na has 11 p+ and 11 e- which gives a 0 charge
If Na loses 1 electron it now has 10 e- vs 11 p+ giving Na+1
Sodium is now an ion

9. Ion An atom or group of atoms that has a positive or negative charge
Examples
Single Ion = Na Sodium Ion
Polyatomic Ion = NH Ammonium Ion
Polyatomic Ions get treated as 1 ion, not separate elements
There is a list of common polyatomic ions in your reference tables

10. Are all Ions Positively Charged?
No!!!!!
Positive Ions are called Cations
Mainly formed from metals
Formed when an atom loses an electron
Negative Ions are called Anions
Mainly formed from metalloids or non metals
Formed when atoms gain electrons

11. Anions
When Chlorine gains an electron, it now has 12 e- and 11p- giving it a -1 charge
Cl-1

12. How do you know how many electrons you need to gain or lose?
In order to be stable you must obey the octet rule!!!!
When forming compounds atoms tend to achieve a noble gas configuration
Must have 8 valence electrons
Oct = 8
Exception is Helium because Helium only has 2 total electrons and one energy level
Octet refers to the ns2 np6 configuration
Trying to achieve a noble state configuration

13. Example Cation Na – e-  Na+1 1s2 2s2 2p6 3s1  1s2 2s2 2p6
1s2 2s2 2p6 = Neon
Anion
Cl + e-  Cl+1
1s2 2s2 2p6 3s2 3p5  1s2 2s2 2p6 3s2 3p6
1s2 2s2 2p6 3s2 3p6  Argon

14. Worksheet

15. Formation of Ionic Compounds
1s2 2s2 2p6 3s s2 2s2 2p6 3s2 3p5
Na Cl:
1s2 2s2 2p6 1s2 2s2 2p6 3s2 3p6 .. . . ..

16. Writing Ionic Chemical Formulas
First, find the oxidation numbers of the elements
Second, place the element with the positive oxidation first
Third, add the two oxidation number together – if they equal zero get rid of the numbers and combine the elements
Fourth, if the oxidation numbers don’t equal zero, criss cross the numbers and write them as subscripts

17. Example
Fluorine and Lithium
F-1 Li +1
 Li +1 F-1
 = 0
 LiF

18. Example Sulfur and Potassium S-2 K+1  K+1 S-2  +1 + -2 don’t = 0
 Criss Cross Oxidation #’s
 SK2

19. Naming Ionic Compounds
These rules are for binary ionic compounds
First, write the cation’s elemental name
Second, to the anion, drop the ending and add –ide
Write the formula with the cation first and anion second

20. Example: Na2Se Na = Na+ = Sodium Se = Se- = Selelenium = Selenide
Sodium Selenide

21. Properties of Ionic Compounds
Solid Crystals at room temperature
Generally have high melting points
Ionic compounds can conduct electricity

22. Activities
Crystal Lab
Water Hardness

23. Bonding In Metals
Valence electrons of metal atoms can be modeled as a sea of electrons

24. Metallic Bonds
Unlike ionic bonds which are formed between a metal and non-metal, metallic bonds are formed between metal atoms