1. BONDS

2. Chemical bonding Joining of atoms to form new substances
A force of attraction that holds atoms together
Atoms bond to each other based on their valence electrons (electrons in outer energy level)
Atoms bond by gaining, losing, or sharing electrons to fill outer energy level with 8 electrons. (except H and He which need 2)

3. Three Types of Bonds
Ionic
Covalent
Metallic

4. Ionic bonds – loss and gain
Ion- charged particles, a charged atom
Ionic bonds are a force of attraction between ions
In ionic bonding a transfer of electrons occurs, an atom gains electrons while the other loses electrons
Bonds between metals and nonmetals

5. Example of ionic bonds Static cling, casts, and seashells
Salt (NaCl)- Sodium(Na) is in group 1, chloride(Cl) is in group 7
Losing an electron makes the atom a positive ion, gaining turns it into a negative ion. But combined the compound is neutral.
Usually metal to nonmetal : the metal loses the electron and the nonmetal gains it

6. Covalent Bonds - share Co means to share
Electron dot diagram is used to represent shared electrons
These bonds are called molecules
Shared electrons are attracted to the nuclei of all atoms involved
Ex. Water (H O), sugar, carbon dioxide (CO )
Nonmetal to nonmetal 2 2

7. Metallic - Pool
Form a pool of electrons which gives metallic bonds unique characteristics
These bonds are malleable (can be hammered into thin sheets) and ductile (can be drawn into a wire)
The pooling (free moving )allows electrons to flow easily so they don’t break and carry electricity well
Ex. Copper, aluminum, gold
Metal to metal

8. Electron Dot Diagram
Shows an atom and the electrons in its outer energy level
Shows symbol of atom and dots around it to represent electrons
Remember, group/family # tells us how many valence electrons (which tells us what type of bond will form)

9. How to write electron dot diagram
Start by putting one dot at the top of the symbol
Then add dots around the symbol in the shape of a box (one one the right, bottom, left)
Add fifth dot to top to make a pair
* you should never have more than eight dots around the symbol

10. Dot diagrams Na C Be Br Sb