Chapter 2: Analyzing DataChapter 2: Analyzing Data

CHEMISTRY

Matter and Change

Section 2.1 Units and Measurements

Section 2.2 Scientific Notation and Dimensional Analysis

Section 2.3 Uncertainty in Data

Section 2.4 Representing Data

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CHAPTER

2 Table Of Contents

• Define SI base units for time, length, mass, and temperature.

mass: a measurement that reflects the amount of matter an object contains

• Explain how adding a prefix changes a unit.

• Compare the derived units for volume and density.

SECTION

2.1 Units and Measurements

base unit

second

meter

kilogram

Chemists use an internationally recognized system of units to communicate their findings.

kelvin

derived unit

liter

density

SECTION

2.1 Units and Measurements

• 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 and Measurements

Units

SECTION

2.1 Units and MeasurementsSECTION

2.1 Units and Measurements

Units (cont.)

SECTION

2.1 Units and Measurements

Units (cont.)

• The SI base unit of time is the second (s), based on the frequency of radiation given off by a cesium-133 atom.

• The SI base unit for length is the meter (m), the distance light travels in a vacuum in 1/299,792,458th of a second.

• The SI base unit of mass is the kilogram(kg), about 2.2 pounds

SECTION

2.1 Units and Measurements

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 Units and Measurements

Units (cont.)

• Not all quantities can be measured with SI base units.

• A unit that is defined by a combination of base units is called a derived unit.

SECTION

2.1 Units and Measurements

Derived Units

• Volume is measured in cubic meters (m3), but this is very large. A more convenient measure is the liter, or one cubic decimeter (dm3).

SECTION

2.1 Units and Measurements

Derived Units (cont.)

• Density is a derived unit, g/cm3, the amount of mass per unit volume.

• The density equation is density = mass/volume.

SECTION

2.1 Units and Measurements

Derived Units (cont.)

Which of the following is a derived unit?

A. yard

B. second

C. liter

D. kilogram

Section CheckSECTION

2.1

What is the relationship between mass and volume called?

A. density

B. space

C. matter

D. weight

Section CheckSECTION

2.1