compounds. compound: a substance made up of atoms of different elements joined together (involves a...
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Compound: a substance made up of atoms of different elements joined together (involves a chemical change)
Example: *There is no atom of water.*Two atoms of hydrogen join with one atom of oxygen. (chemical bond)*The smallest unit of water is called a molecule.
Chemical Formula: the arrangement of symbols and numbers that describe a compound
Example: H2O H = Hydrogen How many atoms of hydrogen? 2 atoms of hydrogen
O = OxygenIf there is no number behind the element symbol, there is just one atom of that element.
Therefore, there is only 1 atom of oxygen in H20.
NaCl How many elements? 2 Name of elements Sodium, chlorine Atoms of each element Na = 1 Cl = 1 Total # of atoms 2 Name of compound Table Salt
Other Chemical Formulas
one atom of nitrogen two atoms of oxygen NO2 nitrogen dioxide
aluminum oxide two atoms of aluminumthree atoms of oxygenAl2O3
acetylenetwo atoms of carbontwo atoms of hydrogenC2H2
sodium carbonatetwo atoms of sodiumone atom of carbonthree atoms of oxygenNa2CO3
glucosesix atoms of carbontwelve atoms of hydrogensix atoms of oxygenC6H12O6
ammoniaone atom of nitrogenthree atoms of hydrogenNH3
benzenesix atoms of carbonsix atoms of hydrogenC6H6
Recipes for Compound Molecules
Write the following as a formula: # 1. hydrogen peroxide two atoms of hydrogen, two atoms of oxygen H2O2
Here are some formulas. You write out the recipe.
# 1. aluminum phosphate AlPO4 one atom of aluminumone atom of phosphorusfour atoms of oxygen
Do you know how to read formulas? Read through the following formulas for molecules of different compounds. Then tell how many different elements and atoms are in each molecule.
# 4. Fe2O3 # of elements 2 # of atoms 5common name rust
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