1. Chemical Formulas2. Counting Atoms3. The Rules of BondingHow do we make larger particles than atoms?

Chemical Formulas- Shorthand way to write a chemical molecule or compound

• SYMBOL-shorthand for one atom of an element

• SUBSCRIPT-• Lower right corner (behind the symbol)• Tells you number or atoms for that element• If there is no subscript-it means one atom

• COEFFICIENT-• In front of formula• Tells you how many molecules you have• All elements are multiplied by that number

Chemical Formula Examples- Ways you may see molecules/compounds written

Ba

Cl2

Ba means Barium- if no subscript you only have one

There is a subscript of 2 so this means you have 2 Chlorine atoms

H 2 SO4

There is a subscript of 2 behind the H so there are 2 Hydrogen Atoms.How many atoms of Sulfur? How many atoms of Oxygen?

Chemical Formula Examples- Ways you may see molecules/compounds written

Ca3(PO4)

2

2NaSO4

There is a coefficient of 2 in front of the whole formula. This means all the elements in the formula are multiplied by 2

NaSO4 + NaSO4

When you have a subscript outside parenthesis, you multiply each element INSIDE them by that subscript

Examples to start with:

2H2O

3Na2SO4

4Pb(NO3)

2

How many molecules?How many Hydrogens? Oxygens?

How many molecules?How many Hydrogens? Sulfurs? Oxygens?

How many molecules?How many Leads? Nitrogens? Oxygens?

MORE VOCABULARY• MOLECULE: 2 or more atoms bonded together

• COMPOUND: 2 or more different atoms bonded together

• This happens during CHEMICAL BONDING• IONIC BONDING -bonding between a ratio of metals and

nonmetals• COVALENT BONDING- bonding between two or more

nonmetals

RULES OF BONDING• TWO TYPES TO KNOW FOR NOW:• IONIC BONDING -bonding between a ratio of metals and

nonmetals• COVALENT BONDING- bonding between two or more

nonmetals

• RULES FOR EACH FAMILY:• Alkali Metals, Halogens, and Hydrogen make only ONE

bond• Alkaline Earth Metals, and Chalogens make TWO bonds• Boron Group and Nitrogen Group makes THREE bonds• Carbon Group makes FOUR bonds• Noble gases make NO BONDS!• Transition metals depends on the individual element.

Counting Atoms Examples

• 2H2O• Molecules of H2O: 2

• H (Hydrogen) : 4• O(Oxygen) : 2

• 3Na2SO4

• Molecules of Na2SO4 3

• Na (Sodium) 6• S (Sulphur) 3• O (Oxygen) 12

Counting Atoms Examples

• 4Pb(NO3)2

• Molecules of Pb(NO3)2 4

• Pb (Lead) 4• N (Nitrogen) 2• O (Oxygen) 6