CompoundsCompounds

CompoundCompound: :

a substance made up of a substance made up of atoms of different elements atoms of different elements joined together (involves a joined together (involves a chemical change) chemical change)

ExampleExample: :

*There is no atom of water.*There is no atom of water.

*Two atoms of hydrogen join with one *Two atoms of hydrogen join with one atom of oxygen. (chemical bond)atom of oxygen. (chemical bond)

*The smallest unit of water is called a *The smallest unit of water is called a molecule.molecule.

Chemical FormulaChemical Formula: :

the arrangement of the arrangement of symbols and numbers symbols and numbers that describe a compound that describe a compound

ExamplExample: e:

HH22O O

H = Hydrogen H = Hydrogen

How many atoms of How many atoms of hydrogen? hydrogen?

2 atoms of hydrogen2 atoms of hydrogen

O = OxygenO = Oxygen

• If there is no number behind the If there is no number behind the element symbol, there is just one element symbol, there is just one atom of that element.atom of that element.

• Therefore, there is only 1 atom of Therefore, there is only 1 atom of oxygen in Hoxygen in H220.0.

NaClNaCl

How many elements? How many elements? 2 2

Name of elements Name of elements Sodium, chlorine Sodium, chlorine

Atoms of each element Atoms of each element Na = 1 Na = 1

Cl = 1 Cl = 1

Total # of atoms Total # of atoms 2 2

Name of compound Name of compound Table Salt Table Salt

Your TurnYour Turn

Other Chemical FormulasOther Chemical Formulas

one atom of nitrogen one atom of nitrogen

two atoms of oxygen two atoms of oxygen

NONO22

nitrogen dioxidenitrogen dioxide

aluminum oxide aluminum oxide

two atoms of aluminumtwo atoms of aluminum

three atoms of oxygenthree atoms of oxygen

AlAl22OO3 3

acetyleneacetylene

two atoms of carbontwo atoms of carbon

two atoms of hydrogentwo atoms of hydrogen

CC22HH22

sodium carbonatesodium carbonate

two atoms of sodiumtwo atoms of sodium

one atom of carbonone atom of carbon

three atoms of oxygenthree atoms of oxygen

NaNa22COCO33

glucoseglucose

six atoms of carbonsix atoms of carbon

twelve atoms of hydrogentwelve atoms of hydrogen

six atoms of oxygensix atoms of oxygen

CC66HH1212OO66

ammoniaammonia

one atom of nitrogenone atom of nitrogen

three atoms of hydrogenthree atoms of hydrogen

NHNH33

benzenebenzene

six atoms of carbonsix atoms of carbon

six atoms of hydrogensix atoms of hydrogen

CC66HH66

Recipes for Compound Molecules Recipes for Compound Molecules

Write the following as a formula: Write the following as a formula:

# 1. hydrogen peroxide# 1. hydrogen peroxide

two atoms of hydrogen, two atoms of two atoms of hydrogen, two atoms of oxygenoxygen

HH22OO22

Here are some formulas. Here are some formulas. You write out the recipe.You write out the recipe.

# 1. aluminum phosphate # 1. aluminum phosphate

AlPOAlPO44

one atom of aluminumone atom of aluminum

one atom of phosphorusone atom of phosphorus

four atoms of oxygenfour atoms of oxygen

Do you know how to read Do you know how to read formulas? Read through the formulas? Read through the following formulas for molecules following formulas for molecules of different compounds. Then of different compounds. Then tell how many different elements tell how many different elements and atoms are in each molecule.and atoms are in each molecule.

# 4. Fe# 4. Fe22OO33

# of elements# of elements 22

# of atoms# of atoms 55

common namecommon name rustrust

Click for Video Clip on Compounds