sig figs PPT slides.pdf

1. Digits from 1-9 are always significant 2. Zeros between two other significant digits are always significant 3. Zeros used solely for spacing the decimal point (leading zeros) are NOT significant 4. Trailing zeros WITH a decimal are significant 5. Trailing zeros WITHOUT a decim...

1. Digits from 1-9 are always significant 2. Zeros between two other significant digits are always significant 3. Zeros used solely for spacing the decimal point (leading zeros) are NOT significant 4. Trailing zeros WITH a decimal are significant 5. Trailing zeros WITHOUT a decimal are NOT significant Rules for Counting Significant Figures Digits from 1-9 are always significant 32.1 g 122 mL 213.12 m.992 s 1.11 cm Rule #1 Zeros between two other significant digits are always significant – “Sandwich Rule” 303 degrees 2.1002 mL.101 g 2003 people 99.02 m 122,001 slightly salty steaks Rule #2 Zeros used solely for spacing the decimal point (placeholders) are NOT significant – “Leading Zeros Rule” 0.0123 mg 0.000000445 mL 0.002 g 0.1 mL 0.089 cm Rule #3 One or more additional zeros to the right of both the decimal point and another significant digit are significant. 21.0 cm.5310 L 101.0 degrees 3033.300 kg.90910 mg Rule #4 If a decimal is NOT included for a whole number, rightmost zeros are NOT significant. 2300 km 120 students 500 mg 10 sandcastles 10,120 lab rats 60,000 s Rule #5  2.12 mg 3 700. N 3 0.001 L 1 3.00 kg 3 705.001 6 90 water buffalo 1 Let’s Mix it Up!  Review Counting Sig Figs Finish Even MORE about Significant Figures Density Basics Today in Science Rule – the answer is rounded to the least number of decimal places in the problem. 2.12 + 3.2 = 5.32 → 5.3 0.23 + 0.312 = 0.542 → 0.54 122 + 233.1 = 355.1 → 355 88 – 13.2 = 74.8 → 75 Rounding Answers in Addition/Subtraction Problems Rule – the answer is rounded to the least number of significant figures in the problem. 2.3 × 24.2 = 55.66 → 56 0.302 × 1.233 = 0.372366 → 0.372 988 / 10.3 = 95.9223301 → 95.9 900. / 10 = 90 → 90 Rounding Answers in Multiplication/Division Problems