1. N UMBERS, S YMBOLS AND C ONVENTIONS USED IN CHEMISTRY Dr. Chin Chu River Dell Regional High School

2. C HEMICAL FORMULAS AND EQUATIONS

3. T HE CONVENTIONS NAME 1. 2. 3.(4) 1.Coefficients 2.Charge number / oxidation state 3.Subscripts 4.Subscripts in ( ) – state of matter

4. C OEFFICIENTS NAME 1. i.Coefficient is a whole number that specifies the number of entities in totality immediately following it. ii.By convention, 1 is usually not written explicitly. Examples: 3H2O3H2O 3 x 2 = 6 H 3 x 1 = 3 O 5 Fe 2 (SO 4 ) 3 5 x 2 = 10 Fe 5 x 3 x 1 = 15 S 5 x 3 x 4 = 60 O

5. S UPERSCRIPTS ( CHARGE #/ OXIDATION STATE ) NAME 2. i.Charge number/oxidation state specifies the charge on the ion. ii.By convention, charge numbers/oxidation states are not included in writing the compound formulas. Examples: Ca 2+ SO 4 2- calcium cation, monoatomic sulfate anion, polyatomic CaSO 4 calcium sulfate compound +

6. SUBSCRIPTS NAME 3. Examples: i.Subscript specifies the number for the element (and that element only) immediately to the left. ii.By convention, subscript 1 is not explicitly written. iii.For polyatomic ions, subscript outside the () covers all elements within the (). SO 4 2- The number 4 only specifies that there are 4 oxygen atoms in the sulfate polyatomic anion. Fe 3 (PO 4 ) 2 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.

7. S UBSCRIPTS IN ( ) – STATE OF MATTER NAME (4) Examples: i.State of matter specifies the state of each compound is in. ii.Could be aqueous (aq), solid (s), liquid (l), gas (g) or precipitate (p). Ca 2+ (aq) calcium cation in water CO 2(g) carbon dioxide gas BaSO 4(p) barium sulfate precipitate