Writing the Formulas of Covalent Compounds
1) Write the symbol/formula of the first element in the compound’s name, then the
symbol/formula of the second ion in the compound’s name.
2) Indicate how many of each element the molecule contains using subscripts after the atomic
symbol.
The numbers of atoms are given in the molecule’s name in Greek prefixes
•
NOTE: If there is no Greek prefix in front of the first element in the name, that
•
means the number is 1.
Example: Write the formula of dinitrogen tetrafluoride.
1) Write the symbol/formula of the first element in the compound’s name, then the
symbol/formula of the second ion in the compound’s name.
N F
2) Indicate how many of each element the molecule contains using subscripts after the atomic
symbol.
N F
The numbers of atoms are given in the molecule’s name in Greek prefixes.
•
dinitrogen tetrafluoride
•
see your chapter 3 notes for a list of the Greek prefixes
•
N
F
2
4
NOTE: If there is no Greek prefix in front of the first element in the name, then
•
the number is 1.
Example carbon tetrachloride = CCl
•
4
Example: Write the formula of carbon disulfide.
1) Write the symbol/formula of the first element in the compound’s name, then the
symbol/formula of the second ion in the compound’s name.
C S
2) Indicate how many of each element the molecule contains using subscripts after the atomic
symbol.
C S
The numbers of atoms are given in the molecule’s name in Greek prefixes.
•
carbon disulfide
•
see your chapter 3 notes for a list of the Greek prefixes
•
C
S
= CS
1
2
2
NOTE: If there is no Greek prefix in front of the first element in the name, then
•
the number is 1.
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