Chemical Names and
Formulas
319-1 (II) name and write formulas
of some common ionic
compounds (both binary and
complex), using the periodic table,
a list of ions, and appropriate
nomenclature for metal and non-
• Compounds that contain two different
elements are called binary compounds.
• Examples: NaCl, MgCl2, H2O
• Count the capitals to find out how
many elements are in the compound
• KOH - is it a binary compound? Why or
why not?
• It is not because it has three elements
(three capital letters)
• If the name of a compound ends in the
suffix –ide, then it is usually (but not
always) binary.
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Copy these compounds into your notebook.
HCl
SO3
MgCO3
KOH
NaCl
CH4
Which are binary?
Which are binary ionic? Which are binary
molecular compounds?
Which of the following are ionic? Which are
molecular compounds?
Sodium sulfide Na2S
PCl3
Nitrogen dioxide NO2
Zinc oxide ZnO
MgI2
• When naming a binary ionic compound the
element that forms the anion (usually nonmetals) usually changes to an –ide
• E.g. NaCl = sodium chloride
• MgO = magnesium oxide
• CaF2 = calcium flouride
Element
Anion
Name
Symbol
fluorine
F
Name
fluoride
chloride
bromide
oxide
sulfide
nitride
Symbol
F-
• More than one atom or ion in a compound
are specified with subscript.
• For example, the formula for calcium
chloride is CaCl2
• This means that for each 1 calcium ion,
there are 2 chloride ions
• I will explain using electron dot diagrams
The X-Rule or
The Cross-Over Method
• Copy these compounds into your
notebooks
• NaO
• MgCl
• LiS
• BeF
• CH
• KO
Try these on your own …
• Copy these formulas into your notebook.
Tell whether they are correct. IF they are
not correct, fix them.
• LiO
• MgO
• K2S
• AlBr3
• Use the Cross-over method (x-rule) to write
the following formulas.
• beryllium fluoride
• sodium nitride
• calcium sulfide
• lithium oxide
• magnesium nitride
• gallium sulfide
• barium bromide
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Answers
BeF2
Na3N
CaS
Li2O
Mg3N2
Ga2S3
BaBr2
• P. 113
• #7, 8