Chemistry: the field of study concerned with the characteristics, composition, and transformations of matter • Matter: anything that has mass and occupies space • Living and non-living • Macroscopic and microscopic
Structure Determines Properties • Everything is made of tiny pieces called atoms and molecules. • Chemists believe that the properties of a substance are determined by the kinds, numbers, and relationships between these pieces.
The Scientific Method • A process for trying to understand nature by observing nature and the way it behaves, and by conducting experiments to test our ideas. • Key characteristics of the scientific method include Observation, formulation of Hypotheses, Experimentation, and formulation of Laws and Theories.
Qualitative Data obtained from one’s opinion Does not involve numbers Quantitative Data obtained from measurements Involves numbers Data
U.S. Customary System • Also called: • American System • English System • Inch • Gallon • Pound • Teaspoon
Metric System • Système International (SI) • International decimalized system of measurement • First adopted by France in 1791 • Meter • Gram • Liter
Length • How long something is… • SI unit = meter (m)
Mass • Measure of the quantity of matter (stuff) in an object • SI unit = Kilogram (kg)
Volume • The amount of space that an object or substance occupies. • SI unit = Cubic meter (m3) • 1 L = 0.001 m3 • 1 L = 1000 mL • 1 mL = 1 cm3 = 1 cc
Time • Duration of event • SI unit = Second (s)
1. Dimensional Analysis • Using units as a guide to problem solving is called dimensional analysis • Figure out which unit you want to start with and which one you want to get to • Use conversion factors to get there • Relationship between two units • May be exact or measured • Generated from equivalence statements • Always include units in your calculations!
Problems • Green light has a wavelength of approximately 550 nm. What is this value in meters? Picometers? Kilometers?
Your neighbor lost 50 pounds. How many kg did she lose? How many micrograms? • How many milliseconds in a year?
Temperature • A measure of the average kinetic energy of the particles in a sample of matter, expressed in terms of units or degrees designated on a standard scale. • A physical property that determines the direction of heat flow in an object upon contact with another object. • Fahrenheit(°F),Celsius (°C),Kelvin(K)
ºF = ºC(1.8) + 32 ºC = (ºF – 32)/1.8 K = ºC + 273 ºC = K – 273 Fahrenheit (ºF), Celsius (ºC), Kelvin (K)
Problems Using Equations: temperature, density, molarity, ideal gas law, etc. • You are feeling sick and decide to take your temperature. Your thermometer, which only reads temps in Kelvin, says that you are at approximately 312 K. Do you have a fever?
Density = m/V (mass/volume) A ring has a mass of 5.84 g and a volume of 0.556 ml. What is it’s density? If the density of platinum is 21.4 g/ml, is the ring made of platinum?
Percentages: set up a ratio (usually the smaller number over the larger number) X 100 to get the %. If there were 40 questions on your test and you got 28 correct, what was your grade as a percentage?