NUMBERS SYMBOLS AND CONVENTIONS USED IN CHEMISTRY Dr

NUMBERS, SYMBOLS AND CONVENTIONS USED IN CHEMISTRY Dr. Chin Chu River Dell Regional High School

CHEMICAL FORMULAS AND EQUATIONS 3 H 2 O O 2 (g) -1 OH CO 2

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

COEFFICIENTS 1. NAME i. ii. Coefficient is a whole number that specifies the number of entities in totality immediately following it. By convention, 1 is usually not written explicitly. Examples: 3 H 2 O 5 Fe 2(SO 4)3 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

SUPERSCRIPTS (CHARGE #/OXIDATION STATE) NAME i. ii. 2. 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: Ca 2+ calcium cation, monoatomic + SO 42 - sulfate anion, polyatomic Ca. SO 4 calcium sulfate compound

SUBSCRIPTS NAME 3. 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 (). Examples: SO 4 Fe 3(PO 4) 2 2 - 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.

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