Matter And Measurement © 2009, Prentice-Hall, Inc. Chapter 1 Introduction: Units of Measurement Chemistry, The Central Science, 11th edition Theodore L. Brown, H. Eugene LeMay, Jr., and Bruce E. Bursten Dr.Imededdine Arbi Nehdi Chemistry Department, Science College, King Saud University

Matter And Measurement © 2009, Prentice-Hall, Inc. Chemistry In this science we study matter and the changes it undergoes.

Matter And Measurement © 2009, Prentice-Hall, Inc. Matter We define matter as anything that has mass and takes up space.

Matter And Measurement © 2009, Prentice-Hall, Inc. Matter Atoms are the building blocks of matter.

Matter And Measurement © 2009, Prentice-Hall, Inc. Matter Atoms are the building blocks of matter. Each element is made of the same kind of atom.

Matter And Measurement © 2009, Prentice-Hall, Inc. Matter Atoms are the building blocks of matter. Each element is made of the same kind of atom. A compound is made of two or more different kinds of elements.

Matter And Measurement © 2009, Prentice-Hall, Inc. States of Matter

Matter And Measurement © 2009, Prentice-Hall, Inc. Properties and Changes of Matter

Matter And Measurement © 2009, Prentice-Hall, Inc. Types of Properties Physical Properties… –Can be observed without changing a substance into another substance. Boiling point, density, mass, volume, etc. Chemical Properties… –Can only be observed when a substance is changed into another substance. Flammability, corrosiveness, reactivity with acid, etc.

Matter And Measurement © 2009, Prentice-Hall, Inc. Types of Properties Intensive Properties… –Are independent of the amount of the substance that is present. Density, boiling point, color, etc. Extensive Properties… –Depend upon the amount of the substance present. Mass, volume, energy, etc.

Matter And Measurement © 2009, Prentice-Hall, Inc. Types of Changes Physical Changes –These are changes in matter that do not change the composition of a substance. Changes of state, temperature, volume, etc. Chemical Changes –Chemical changes result in new substances. Combustion, oxidation, decomposition, etc.

Matter And Measurement © 2009, Prentice-Hall, Inc. Units of Measurement

Matter And Measurement © 2009, Prentice-Hall, Inc. Many properties of matter are quantitative; that is, they are associated with numbers. When a number represents a measured quantity, the units of that quantity must always be specified. To say that the length of a pencil is 17.5 is meaning less. To say that it is 17.5 centimeters (cm) properly specifies the lenght. The units used for scientific measurements are those of the metric system. In 1960 an international agreement was reached specifying a particular choice of metric units for use in scientific measurements. These preferred units are called SI units, after the French Systeme International d`Unites. The SI system has seven base units (Table 1.1) from which all other units derived.

Matter And Measurement © 2009, Prentice-Hall, Inc. TABLE 1.1 SI Base Units Prefixes are used to indicate decimal fractions or multiples of various units. For example, the prefix milli- represents a fraction of a unit: a milligram (mg) is gram(g), a millimeter (mm) is meter (m), and so forth. Table 1.2 presents the prefixes commonly encountered in chemistry.

Matter And Measurement © 2009, Prentice-Hall, Inc. Table 1.2 Selected Prefixes Used in the Metric System Prefixes convert the base units into units that are appropriate for the item being measured.

Matter And Measurement Non- SI Units -Although non-SI units are being phased out, there are still some that are commonly used by scientists such as Celsius, Gallon, Pound, …. -1 Gallon = liter -1 pound = kilograms

Matter And Measurement © 2009, Prentice-Hall, Inc. Units of Temperature By definition temperature is a measure of the average kinetic energy of the particles in a sample. Conversions: K =  C  F = 9/5(  C) + 32  C = K − )  C = 5/9(  F − 32)

Matter And Measurement Derived SI Units -The SI units are used to derive the units of other quantity such as pressure, speed, force …. -For example, speed is defined as the ratio of distance to elapsed time. Thus the SI unit for speed is the SI unit for distance (length) divided by the SI unit for time, m/s, which we read as `` meter per second``. -SI unit of force is (kg.m)/s 2 called newton (N) - SI unit of pressure is kg/m.s 2 called pascal (Pa)

Matter And Measurement © 2009, Prentice-Hall, Inc. Volume The most commonly used metric units for volume are the liter (L) and the milliliter (mL). –A liter is a cube 1 dm long on each side. –A milliliter is a cube 1 cm long on each side. –1 L = 1 dm 3 –1 L = 1000 mL = 1000 cm 3 –1 m 3 = 1000 L

Matter And Measurement © 2009, Prentice-Hall, Inc. Density Density is a physical property of a substance. It defined as the amount of mass in a unit volume of the substance The densities of solids and liquids are commonly expressed in (g/cm 3 ) or (g/mL). d = mVmV