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Chemistry. Chapter 2 Math. Vocabulary. Scientific method : the strategy to explore a problem Qualitative : words Quantitative: numbers Accuracy : the measurement approaches true value of quantity Precision : the same quantity, made in same ways, and agrees with one another
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Chemistry Chapter 2 Math
Vocabulary • Scientific method : the strategy to explore a problem • Qualitative : words • Quantitative: numbers • Accuracy : the measurement approaches true value of quantity • Precision : the same quantity, made in same ways, and agrees with one another • Significant Figures (SF) : consists of all the digits known with certainty plus final digits * Zeros in the beginning never, zeros in the middle always, zeros in the end sometimes if following a decimal point. • Addition/Subtraction with SF and SN : must have the same number of digits to right of the decimal point as there are in measurement having fewest digits • Multiplication/Division with SF and SN : D = M V ; no more SF’s than what are in the measurement with fewest number of SF. • Density : the ratio of mass to volume, or mass divided by volume. D = M V • Factor Label Method (Conversion Factors) : change one unit into another; converting numbers • Metric System : system of measurements • SI units : terms of standard measurement
Math • “Sig figs” : 305 = 3 sf’s 0.1 = 1 sf , 0.01090 = 4 sf’s • Adding/ subtracting Sig Figs: 2.44cm +100. cm +14.5667 =117.0067 = 117. cm / 3.467 mm – 0.02 = 3.447 = 3.45 mm • Multiplying/ dividing Sig Figs : (4.50 cm)(2) = 9. cm / (64.0 g) / (10. mL)= .64g/mL • Density : volume = 55 cm3 & mass = 170 g ; 170g 55cm3 = 3.1g/cm3 • Addition/ subtraction SN : 4 • Multiplying/ dividing SN : 4.67 X 104 = 0.000467
UNITS SI system of units Length Meter m Mass Kilogramkg Time Second s Temperature Kelvin K Amount of substance Mole mol Electric Current Ampere A Intensity of Light Candela cd METRIC PREFIXES PREFIX Unit abbreviation Exponent Factor Tera T 1012 Giga G 109 MegaM 106 Kilok 103 Hecto h 102 Dekada101 Base * 100 Decid 10 -1 Centic10-2 Millim 10-3 Microu 10-6 Nanon 10-9 Pico p 10-12 Femto f 10-15 Atto a 10-18
Scientific Notation 1. Standard form is #.# X 10n . 1.2 X 103 2. A positive exponent is a large number. 1.2 X 103 = 1200 3. A negative exponent is a small number. 5.7 X 10-2 = 0.057 4. The number of sig figs does not change when converting between expanded and scientific notation. 1200 has 2SF as does 1.2 X 103 1200. has 4SF as does 1.200 X 103