measurement: quantity with _______ and a _____ g1.05 mL16 cm Measurement unit number

a really big number: 100,000,000,000,000 (atoms in a cell) or really small number: meter (size of one atom) can be written without zeroes by using powers of 10. Scientific Notation

100,000,000,000,000 = 1 x atoms (atoms in a cell) meter = 1 x 10 –11 meters (size of an atom) Scientific Notation

AccuratePrecise_______________ Accurate and Precise but not Neither Precise Nor Accurate

Accuracy: how close to the actual or true value Accuracy, Precision, and % Error Precision: how close to each other (repeatable)

Error % Error = (________) x 100 acc Accuracy, Precision, and % Error exp – acc exp – experimental value acc – accepted value

What is the % error if a measurement of 99.1 o C is made, but the true temperature is o C? % Error Calculation:

1.Which of the following expressions has NOT been correctly changed to sci. not.? A = 4.56  10 –3 B = 2.54  10 –5 C.8,426,000 =  10 6 D.45,200 = 4.52  10 3 Quick Quiz!

2. Which set of measurements of a 2.00-g object is the most precise? A.2.00 g, 2.13 g, 1.92 g B.2.10 g, 2.00 g, 2.20 g C.2.05 g, 2.04 g, 2.05 g D.1.50 g, 2.00 g, 2.50 g Quick Quiz.