CHM 111 Lecture Notes - Lecture 2: Significant Figures, Decimal Mark, Kilogram

• School: University of Miami
• Department: Chemistry
• Course: CHM 111
• Professor: Lewis Nita

Document Summary

Zeros that precede the first non-zero digit in the number are not significant: ex: 0. 00174 3 significant figures. Zeros surrounded by non-zero digits are significant: ex: 9006 4 significant figures. Zeros that follow the last nonzero digit are significant if there is a decimal point: ex: 23. 00 4 significant figures. If there is no decimal point, it cannot be determined if zeros at the end of a number are. Avoid doing this: ex: 700 may have 1, 2, or 3 significant figures (cid:402) re-write it as: 7. 00 x 102 = 3 significant figures. 7 x 102 = 1 significant figures (cid:403) (cid:403) rounding off numbers. If the question is asking you to round off to 1 significant figure, then your discarded digit will be the 2nd digit. (cid:402) ex: 44. 444 rounded to 1 significant figure. (cid:403) In this case, the discarded digit is the 2nd four and is less than 5, the last remaining digit, the first one, remains unchanged.