Introduction to Chemistry Chemistry The study of: ◼ the composition (make-up) of matter ◼ the changes that matter undergoes What is matter? ◼ Anything that: ◼ has mass and ◼ occupies space (volume). Mass vs Weight ◼ Mass: a measure of the amount of matter that an object contains. (SI unit kilogram, kg) ◼ Weight: The force with which the earth pulls on an object. (SI unit Newton, N) The 5 Branches of Chemistry ◼ Inorganic ◼ Organic ◼ Analytical ◼ Physical ◼ Biochemistry Inorganic Chemistry ◼ The study of chemicals that do not contain carbon. Organic Chemistry ◼ The study of chemicals that contain carbon. ◼ Origin: study of chemicals in living organisms. Organic or Inorganic ? ◼ Sulfuric Acid H2SO4 ◼ Methane CH4 ◼ Hydrochloric Acid HCl ◼ Ethane C2H6 Analytical Chemistry ◼ Composition of matter. http://besg.group.shef.ac.uk/Facilities/Images/gcms.JPG Ex: Mass Spectrometer Gas Chromatograph Physical Chemistry ◼ The study of : ◼ The mechanism ◼ The rate ◼ The energy transfer that happens when matter undergoes change. Biochemistry ◼ Study of processes that take place in organisms. Science ◼ What? ◼ Why? ◼ How? ◼ When? Science and Technology ◼ Science → Pure ◼ Does not necessarily have an application. ◼ Technology → Applied ◼ Has practical applications in society. ◼ Engineering. Question: Science or Technology? Studying or forming aspirin in a lab in small scale (small amounts). ◼ Producing aspirin tablets so that consumers can use them. Question: Science or Technology? Example: Discovery of Nylon by Wallace Carothers in 1930's http://www.chemheritage.org/EducationalServices/nylon/nylon.html http://heritage.dupont.com/touchpoints/tp_1935-2/depth.shtml MicroscopicMacroscopic ◼ Micro –(small) ◼ Microscopicobjects can be seen with a microscope. ◼ Macro-(from afar) ◼ Macroscopicobjects are seen without a microscope. Part II – A Brief History and the Scientific Method Aristotle (Greece, 4th Century BC) Philosopher who believed that: ◼ There are 4 elements: earth, water, air, fire. ◼ Matter is perpetually divisible. Democritus (Greece, 4th Century BC) ◼ First atomic theory ◼ Atom (indivisible). Alchemists (~300BC-1650 AD) China, India, Arabia, Europe, Egypt •Aiming to: ▪Change common metals to gold. ▪Develop medicines. •Developed lab equipment. Galileo Galilei (Italy 1564 AD) ◼ Father of the scientific method (along with the Englishman Francis Bacon 1500's). Antoine Lavoisier (France 1743-1794) ◼ Regarded as the Father of Chemistry. ◼ Designed equipment. ◼ Used observations and measurements. ◼ Discovered nitrogen. Antoine Lavoisier (cont'd) ◼ Discovered the Law of Conservation of Mass: ◼ In a chemical reaction mass is conserved. ◼ Explained burning as reaction with oxygen. ◼ Old theory: release of "phlogiston". Antoine Lavoisier (cont'd) Question: ◼ Does an iron nail gain mass or lose mass when it rusts (a form of burning)? John Dalton (England 1766-1844) ◼ Atomic theory Amedeo Avogadro (Italy, 1776-1856) ◼ Avogadro's Number 6.02x1023 ◼ One mole of any substance contains 6.02x1023 particles. Dmitri Mendeléev (Russia, 1834-1907) ◼ First Periodic Table of elements. The Scientific Method ◼ Steps followed during scientific investigations. Scientific Method ◼ Observationrecognition of a problem. ◼ Hypothesisa proposed explanation of an observation ◼ an educated guess ◼ must be testable. ◼ Experimenta procedure used to test a hypothesis (measurement, data collection, manipulated and responding variables) ◼ Theory ◼ Law Theory ◼ A well tested explanation for a broad set of observations. ◼ May use models. ◼ May allow predictions. ◼ Theories may change to explain new observations. Law ◼ A statement that summarizes results of observations, but does not explain them. ◼ Changes or is abandoned when contradicted by new experiments. Note: ◼ The order of the steps can vary and additional steps may be added. "No number of experiments can prove me right; a single experiment can prove me wrong." Albert Einstein Part III Math and Chemistry ◼ Maththe language of Science Units ◼ SI Units – International System ◼ Basic Units mks Length (meter) m Mass (kilogram) kg Time (second) s ◼ National Bureau of Standards Solving Word Problems ◼ Analyze ◼ List knowns and unknowns. ◼ Devise a plan. ◼ Write the math equation to be used. ◼ Calculate ◼ If needed, rearrange the equation to solve for the unknown. ◼ Substitute the knowns with units in the equation and express the answer with units. ◼ Evaluate ◼ Is the answer reasonable?