1. Molecules

2. Goal of the class To understand molecules and how they are written
Question of the day: What is the subscript used for?
Previous Answer: New Term – No previous question
Previous question: None

3. Molecules Bonding occurs when atoms take or share valence electrons
When atoms share electrons, they become molecules
Can be same the element (N2)
Different elements (CO2)
Molecules have no limits to the number of atoms that are bonded together

4. Molecular Properties
Once molecules are bonded together they have different properties than individual atoms
Example: water (H2O) has very different properties than hydrogen or oxygen
Atoms bonded together undergo a chemical change
Hardened steel, like in bicycle locks.

5. Chemical Formulae
Chemical formulas will use the atomic symbols to show which atoms are in a molecule
Example: CCl4 (carbon tetrachloride)
It has one carbon atom and four chlorine atoms
The small number near the elements is the subscript
It shows the number of atoms that are bonded Cl C
Sub / superscript
Repeating units
Car not to mistake this for C and I instead of Cl

6. Ions Ions don’t form molecules
They can stick together with other ions or molecules
some ions can be made of more than one atom
Example: Hydronium H3O+ or Hydroxide OH- ions
Hydronium ion
It has one more proton than electrons in the molecule

7. Naming Molecules follow simple naming system with the subscript
Mono- means one
Di- means two
Tri- means three
Negative ions (anion) always end with –ide
Example:
Sodium and chlorine ions gives sodium chloride
Tetra = 4
Penta = 5
Suffix means afterwards

8. Vocabulary
Molecule – The smallest particle of a compound that retains its chemical properties; two or more atoms held together by chemical bonds
Subscript – A type of lettering form that is written lower than the things around it.

9. Homework Please read Chemical Interactions textbook pages 25, 48-51
Please complete Chemical Interactions workbook page 16.