Section 2.1

Section 2.1 Units and Measurements Define SI base units for time, length, mass, and temperature. Explain how adding a prefix changes a unit. Compare the derived units for volume and density. mass: a measurement that reflects the amount of matter an object contains

activities and products Comprehension Verbs activities and products explain interpret outline discuss distinguish predict restate translate compare describe draw pictures to show a particular event. Illustrate what you think the main idea was. Make a cartoon strip showing the sequence of events. Write and perform a play based on the story. Retell the story in your words. Paint a picture of some aspect you like. Write a summary report of an event. Prepare a flow chart to illustrate the sequence of events. Make a coloring book.

Units of Measurement Article: 26, 48 Terms: 25 Mastering Concepts: 50 (52-57) Lab: 28 copy table: p. 26 (2-1) and (2-2) Practice Problems: 29 (1-3) Homework: Cornell Notes: 2.1 Section Assessment: 30(4-9) Mastering Problems: 50 (72-74) 11 Stamps

Section 2-1 Units Système Internationale d'Unités (SI) is an internationally agreed upon system of measurements. A base unit is a defined unit in a system of measurement that is based on an object or event in the physical world, and is independent of other units.

Section 2-1 Units (cont.)

Units (cont.) Section 2-1 m/1G 1m/10dm

Section 2-1 The SI base unit of temperature is the kelvin (K). Units (cont.) The SI base unit of temperature is the kelvin (K). Zero kelvin is the point where there is virtually no particle motion or kinetic energy, also known as absolute zero. Two other temperature scales are Celsius and Fahrenheit.

Section 2-1 Derived Units (cont.) Density is a derived unit, g/cm3, the amount of mass per unit volume. The density equation is density = mass/volume.

Mastering Concepts: 50(52-57)

52. Why must a measurement include both a number and a unit? (2.1) Mastering Concepts 52. Why must a measurement include both a number and a unit? (2.1) The number gives you the quantitative value, and the unit indicates what was measured. 53. Explain why scientists, in particular, need standard units of measurement. (2.1) Scientists from different countries have different languages and cultures but must be able to share and compare data.

54. What role do prefixes play in the metric system? (2.1) Prefixes give the magnitude of the measurement. 55. How many meters are there in one kilometer? In one decimeter? (2.1) 1000; 0.1 56. What is the relationship between the SI unit for volume and the SI unit for length? (2.1) The SI unit for volume is the cubic meter, m3, which is equal to three SI measurements of length multiplied together.

Section 2-1 A more convenient measure is the liter Derived Units (cont.) A more convenient measure is the liter

57. Explain how temperatures on the Celsius and Kelvin scales are related. (2.1) The sizes of the units are equal; °C + 273 = K.

Displacement Volume It's the way to figure out the volume of an irregular object. The volume is the amount of water that has been displace after putting in the object. Displace: how water level changes after adding an object The difference of initial and Final volume

Volume Displacement It's the way to figure out the volume of an irregular object. The volume is the amount of water that has been displace after putting in the object. Displace: how water level changes after adding an object

Density involves 2 quantities one relationship Grams (mass) Cubic centimeter (volume) one relationship Grams/cm3

Practicing Problems 29(1-3)

page 29 Practice Problems 1. A piece of metal with a mass of 147 g is placed in a 50-mL graduated cylinder. The water level rises from 20 mL to 41 mL. What is the density of the metal? Density = mass/volume Volume = 41 mL – 20mL = 21 mL Density = 147g/21mL = 7.0g/mL

p.29 (2) 2. What is the volume of a sample that has a mass of 20 g and a density of 4 g/mL? Volume = mass/density v o l u m e = density 20 g/4 g / m L =5 m L

3. A metal cube has a mass of 20 g and a volume of 5 cm3 3. A metal cube has a mass of 20 g and a volume of 5 cm3. Is the cube made of pure aluminum? Explain your answer. the density of the cube = mass/volume = 20g/5cm3 = 4 g/cm3. No; the density of aluminum is 2.7 g/cm3

Mastering Problems: 50 (72) Mastering Problems Density (2.1) Level 1 72. A 5-mL sample of water has a mass of 5 g. What is the density of water? Density= mass/ volume = 5 g/5mL = 1g/mL