1) Units of Measurement

• Many properties of matter are quantitative; they are related to numbers.
• The metric system contains the units used for scientific measurements.
• SI units are a particular choice of metric units commonly used in scientific measurements.
• The SI system contains seven base units from which all other units are derived.

• Prefixes are used to indicate decimal fractions or multiples of units.

• The SI base unit for length is meter.
• Mass is the amount of matter in an object; the base unit of mass is kilogram.
• Temperature is the measure of hotness or coldness of an object.
• Temperature is a physical property that determines heat flow.
• Heat always flows from substances of higher temperature to substances of lower temperature.
• The Celsius scale is based on 0^oC as the freezing point of water and 100^oC as the boiling point of water.
• The Kelvin scale is the SI temperature scale; one unit of Kelvin is equal to one unit of Celsius.
• The absolute zero, or 0 K, is the lowest attainable temperature in Kelvin; it equals -273.15^oC; the freezing point of water, 0^oC, is equal to 273.15 K.
• The Fahrenheit scale is not commonly used in scientific studies; 32^oF is the freezing point of water and 212^oF is the boiling point of water.
• K = ^oC + 273.15 , ^oC = (5/9)(^oF – 32) , ^oF = (9/5)(^oC) + 32
• Derived unit are determined by using the defining equation for the quantity and substituting the appropriate base units.
• Volume is defined as length cubed.
• Liter is the non-SI unit for volume; one liter equals one cubic decimeter (dm³).
• Density is used to characterize substances; it is defined as the amount of mass per unit volume.
• Densities depend on temperature; the density of water is 1.00 g/mL of 1.00 g/cm³.