WARM -UP CLASSIFY EACH SUBSTANCE AS APURE SUBSTANCE OR MIXTURE.IF IT’S A PURE SUBSTANCE, CLASSIFY AS AN ELEMENT OR COMPOUND.IF IT’S A MIXTURE, CLASSIFY AS HOMOGENEOUS OR HETEROGENEOUS 1. SWEAT 2.CARBONDIOXIDE 3.ALUMINUM 4.VEGETABLE SOUP

The units of measurements Units – Standard quantities used to specify measurements The two most common systems are the metric system and the English system Scientists use the international system of units that is the metric system

SI base units Quantity Unit Symbol Length Meter M Mass Kilogram Kg Time Second S Temperature Kelvin K Amount of Substance Mole mol Electric Current Ampere A Intensity Candella cd

Definitions Meter – Measure of length – International bureau of weights and measures defined Meter as the distance light travels through vacuum in certain period of time(1/299,792,458 seconds) Kilogram – Measure of Mass – The mass of a metal cylinder kept at the International bureau of weights and measures at France Mass - The measure of quantity of matter within it Weight – The measure of gravitational pull on it The second – The measure of Time – Second is defined by the International bureau of weights and measures duration of 9,192,631,770 periods of the radiation emitted from a certain transition in a Cesium -133 The Kelvin – The SI unit of temperature

Three common temperature scales are 1. Fahrenheat scale (°F) 2 Three common temperature scales are 1.Fahrenheat scale (°F) 2.Celcius scale(°C) 3.Kelvin Scale(absolute scale)

Temperature Measurements SI UNIT OF TEMPERATURE – KELVIN SCALE THE OTHER UNITS OF TEMPERATURE ARE CELCIUS SCALE AND FAHRENHEAT SCALE ABSOLUTE SCALE – ASSIGNS THE COLDEST TEMPERATURE AS 0 KELVIN. THERE IS NO NEGATIVE TEMPERATURE INVOLVED IN KELVIN SCALE AT ABSOLUTE ZERO THERE IN NO OR MINIMAL MOLECULAR MOTION.

Equations ° F = 1.8(K - 273) + 32 °C = (°F-32)/1.8 K = °C+273.5

Temperature – Is the measure of average kinetic energy( energy due to motion) of the atoms or molecules. Temperature also determines the direction of thermal energy transfer called heat. Thermal energy always transfers from hot objects to cold ones

Choosing Prefix Multipliers Scientific notations allows us to express very large or very small quantities in a compact manner You have to choose the prefix multiplier close to the size of the quantity you are measuring Examples: The radius of H atoms can be expressed as 1.06 × 10−10m Kilo –1 km = 1000m= 103M 1mm= .001m = 10−3m

Prefix multipliers