1. Bonding, Formulas, & Reactions

2. Bonding of Atoms
Atoms can attach to other atoms by forming chemical bonds
Bonds are created by gaining, losing, or sharing electrons
2 kinds of chemical bonds:
Ionic Bonds
Covalent Bonds
Atoms bond to try to have a full outer shell of electrons

3. Ionic Bonds
Atoms that lose or gain electrons become electrically charged…these are called ions
EX. Sodium only has 1 electron in its outer shell, so it will lose that electron to become stable— but charged

4. Ionic Bonds
When oppositely charged ions attract, they form a chemical bond called an ionic bond
EX. Sodium and Chlorine

5. Covalent Bonds
Atoms may also bond by sharing electrons rather than by exchanging them
The chemical bond between atoms that share electrons is called a covalent bond
EX. Water

6. Molecules & Compounds
When 2 or more atoms bond, they form a particle called a molecule
When atoms of different elements bond, they form molecules called compounds
ALL COMPOUNDS ARE MOLECULES BUT NOT ALL MOLECULES ARE COMPOUNDS!

7. Formula
A molecular formula represents the numbers and types of atoms in a molecule
Ex. H2O
Count the number of atoms in CH3
C = 1
H = 3
Total = 4 atoms

8. Chemical Reactions
Chemical reactions form or break bonds between atoms, ions, or molecules, generating new chemical combinations
There are 4 kinds of reactions:
Synthesis
Decomposition
Exchange Reaction
Reversible Reaction

9. Synthesis Reactions
When two or more atoms (reactants) bond to form a more complex structure (product), the reaction is called synthesis
Something is being made!
A + B  AB

10. Decomposition Reactions
If the bonds within a reactant molecule break so that simpler molecules, atoms, or ions form, the reaction is called decomposition
AB  A + B

11. Exchange Reaction
In exchange reactions, parts of two different molecules trade positions as bonds are broken and new bonds are formed
AB + CD  AD + CB

12. Reversible Reaction
Reversible reactions are reactions in which the product of the reaction can change back to the reactant.