Numbers, Symbols and Conventions used in chemistry. Dr. Chin Chu River Dell Regional High School. Chemical formulas and equations. 3H 2 O. OH -1. CO 2. O 2 (g). What do those numbers and sy mbols mean?. The conventions. 2. NAME. 1. 3 . (4). Coefficients
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Dr. Chin Chu
River Dell Regional High School
What do those numbers and symbols mean?
Charge number / oxidation state
Subscripts in ( ) – state of matter
Coefficient is a whole number that specifies the number of entities in totality immediately following it.
By convention, 1 is usually not written explicitly.
3 x 2 = 6 H
3 x 1 = 3 O
5 x 2 = 10 Fe
5 x 3 x 1 = 15 S
5 x 3 x 4 = 60 O
Charge number/oxidation state specifies the charge on the ion.
By convention, charge numbers/oxidation states are not included in writing the compound formulas.
calcium cation, monoatomic
sulfate anion, polyatomic
calcium sulfate compound
Subscript specifies the number for the element (and that element only) immediately to the left.
By convention, subscript 1 is not explicitly written.
For polyatomic ions, subscript outside the () covers all elements within the ().
The number 4 only specifies that there are 4 oxygen atoms in the sulfate polyatomic anion.
3 specifies there are three iron (II) cations in the compound.
4 specifies there are four oxygen atoms in each polyatomic phosphate ion.
2 specifies there are two complete phosphate ions in the compound.
State of matter specifies the state of each compound is in.
Could be aqueous (aq), solid (s), liquid (l), gas (g) or precipitate (p).
calcium cation in water
carbon dioxide gas
barium sulfate precipitate