Name: ____________________________________________
Date: _________________
Chemical Formulas & Counting Atoms
_________ are the basic units of matter. Atoms join together chemically to form
elements. Elements are _______ substances made of only one kind of atom and
are organized on the Periodic Table. _______________ is a term used to refer to
2 or more atoms which are bonded. Examples are O2 and CO2. CO2 is both a
molecule and a ______________as well.
Compounds are substances made of two or more _______________ elements
chemically combined in a set ratio. A chemical _________, or electric force, holds
the atoms together in a compound.
The properties of a compound are totally _____________ from the elements
that make up the compound. For example, salt is composed of sodium (Na); a
silvery ___________; and chlorine (Cl); a stinky, green _______. When the two
elements bond to form NaCl, they form solid white crystals which you can eat!
Chemical
_____________ are used to show the ratio of elements in a
compound. The elements present in a compound are identified with the element’s
symbol. If more than 1 atom of an element is in the compound, it is shown with a
____________. For example, water; H2O; has ___atoms of hydrogen. Since
oxygen has no subscript, there is only ___ atom of oxygen.
Sometimes, substances contain ________________ molecule of an individual
compound. This is shown with a ______________. Coefficients are written in
_________ of the compound’s formula.
Ex: 3CO2 means there are ____ molecules of carbon dioxide.
___atoms of carbon + ___ atoms of oxygen = _____ total atoms
Compound
H2O
ZnCO3
Al2O3
3Na2SO3
Name
Use
Elements present
Total # of atoms
water
Supports life
2-hydrogen
1-oxygen
3
zinc
carbonate
aluminum
oxide
Hazardous
substance in
makeup,
plastics, etc.
Used in
ceramics
sodium
sulfate
Used in soaps
and detergents
glucose
Sugar
methane
Flammable gas
used in heating
homes
hydrochloric
acid
Used in steel
pickling, oil well
acidizing, etc.
Calcium
carbonate
Limestone
Aspirin
Pain reliever
Magnesium
hydroxide
Found in milk of
magnesia
Trinitrotolue
ne (TNT)
Explosive
Calcium
dihydrogen
phosphate
Fertilizer
C6H12O6
5CH4
2HCl
CaCO3
2C9H8O4
Mg(OH)2
C7H5(NO2)3
Ca(H2PO4)2
# of
molecules
1