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Numbers, Symbols and Conventions used in chemistry

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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Numbers, Symbols and Conventions used in chemistry

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  1. Numbers, Symbols and Conventions used in chemistry Dr. Chin Chu River Dell Regional High School

  2. Chemical formulas and equations 3H2O OH-1 CO2 O2(g) What do those numbers and symbols mean?

  3. The conventions 2. NAME 1. 3. (4) Coefficients Charge number / oxidation state Subscripts Subscripts in ( ) – state of matter

  4. Coefficients NAME 1. 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 Examples: 3H2O 3 x 1 = 3 O 5 x 2 = 10 Fe 5Fe2(SO4)3 5 x 3 x 1 = 15 S 5 x 3 x 4 = 60 O

  5. Superscripts (charge #/oxidation state) 2. NAME Charge number/oxidation state specifies the charge on the ion. By convention, charge numbers/oxidation states are not included in writing the compound formulas. Examples: Ca2+ calcium cation, monoatomic + sulfate anion, polyatomic SO42- CaSO4 calcium sulfate compound

  6. subscripts NAME 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 (). 3. The number 4 only specifies that there are 4 oxygen atoms in the sulfate polyatomic anion. Examples: SO42- 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. Fe3(PO4)2

  7. Subscripts in ( ) – state of matter NAME State of matter specifies the state of each compound is in. Could be aqueous (aq), solid (s), liquid (l), gas (g) or precipitate (p). (4) Examples: calcium cation in water Ca2+(aq) carbon dioxide gas CO2(g) barium sulfate precipitate BaSO4(p)

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