1. CHEMICALbonding

2. The formation of ionic compounds
Conductivity: physical property of metals, ability of electrons to move freely throughout a material
Few compounds are able to conduct electricity in the solid state
BUT some conduct electricity when dissolved in water
These compounds are called electrolytes
Example: Sodium chloride (table salt); potassium iodide; calcium oxide
Non-electrolytes do not conduct electricity in water
Example: carbon dioxide, methane, silicon dioxide

3. WHY? The other name for electrolytes is IONIC COMPOUND
Ionic compounds consist:
METAL + NON-METAL = IONIC COMPOUND
Atoms can gain or lose electrons in their outer layer to become more stable
They want to have a similar outer shell to their nearest noble gas

4. example Draw the Bohr Diagram for the following elements: Sodium
Fluorine
Neon

5. Making ions
Atoms follow the octet rule: each main group element wants to have eight electrons in its outer shell
Atoms gain or lose electrons to get to 8 in the outer shell
Ion: atom (or group of atoms) that has gained or lost one or more electrons
Anion: an atom that carries a negative charge because it has more electrons than protons
Cation: an atom that carries a positive charge because it has more protons than electrons

6. Valence electrons: electrons that are found in the outer shell (level) of the atom
Metals tend to lose electrons and become cations
Non-metals (except noble gases) tend to gain electrons and become anions

7. Examples
Draw the ions for:
Sodium (Na1+)
Fluorine (F1-)
Neon (Ne)

8. Ionic BONDING Occurs with a metal and non-metal
Example: Sodium Chloride

10. COVALENT BONDING

11. PRACTICE
LiF
SrO
Na2O

12. Most of the chemicals we encounter are molecular compounds, including:
Acetylsalicylic acid, or Aspirin
sugar
water

13. Soft Drinks
Sugar
C12H22O11
Carbon Dioxide
CO2
Water
H2O

14. Living Organisms
Make thousands of different kinds of molecular compounds
Sugars, fats, and proteins are all molecular compounds
Some of them are very large, containing thousands of atoms in a single molecule

15. - more electronegative goes first
compounds
Covalent
- two non-metals
- sharing of electrons
- more electronegative goes first
- form molecules
Ionic
- metal and nonmetal
- transfer of electrons
- cations and anions
- form formula units

16. Molecular Compounds The majority of all known compounds are molecular
Molecules consist of two or more non-metal atoms joined by a covalent bond
A COVALENT BOND forms when atoms share electrons
The chemical formula gives the exact numbers of atoms in each molecule
Diatomic molecules consist of only two atoms of either the same or different elements

19. when two NONMETALS come in contact they will share electrons rather than transferring them, ex. O and O

20. covalent bond
forms as a result of sharing of electrons
very strong, stronger than ionic bond
atoms that are covalently bonded form molecules
when two atoms form a covalent bond the sharing of electrons allows each to satisfy the octet rule

21. Lewis Structures of Molecules
shared electrons are shows as a dash
pairs of valence electrons surrounding each atom and not involved in bonding are called lone pairs
Ex. O2

22. ex. I2, N2, CO2, H20

23. Ionic Bond vs Covalent Bond
An Ionic bond is the simultaneous strong attraction of positive ions and negative ions
A covalent bond results from the sharing of outer electrons between non-metal atoms