Chem 103 1st Edition Lecture 2 Outline of Last Lecture I. What is Chemistry?a. Definition of chemistryII. Mattera.Massb.WeightIII. Properties of Mattera. Physical Propertiesb. Chemical PropertiesIV. Changes of Mattera. Physical Changesb. Chemical ChangesOutline of Current Lecture I. Atomsa. Democritusb. John Daltonc. Chemical View of the Atomd. Elementse. CompoundsII. Measurements and Measurement Unitsa. Metric SystemCurrent LectureAtomsDemocritus (Greek, 460-370 BC)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- First person recorded to suggest that atoms were the basis of matter. He reached this conclusion based on logic, concluding that if we divided a substance in half over and over again, eventually we would reach a point that could not be cut any smaller.- The word “atom” comes from the word “atomos,” meaning “no cut” in Greek- Different types of atoms- Matter made of atoms, spaces were called the void- Democritus’s theory was rejected for nearly 1500 years after Aristotle (384-322 BC) argued against it. Aristotle didn’t believe in the void, and thus rejected the theory.John Dalton (English, 1766-1844)- Father of modern Atomic Theory- Based on experiments with gases- Dalton Atomic Model of Mattero All matter made up of atomso Unique atoms are called elementso Molecules are collections of bonded atomso Compound is the general term that includes molecules, atoms, and ions (atom or molecule with a positive or negative charge)o Compounds have a fixed ratio of atomso Chemical reactions do not destroy or create atomso Chemical reactions can destroy or create compoundsChemical View of the Atom- Nucleus is the center containing protons (+) and neutrons (0)- Electrons (-) are on the outside - Atomic number = number of protons. Defines an element (Oxygen always has 8 protons)- Atomic mass = weight of protons and weight of neutrons- Number of electrons = number of protons in neutral atom- Neutron weight = proton + electron Elements:- Pure substances made up of homoatomic molecules or individual atoms of the same kind- Ex: O2 (oxygen molecule)Compounds:- Pure substances that are made up of atoms bonded to form heteroatomic molecules or individual ions of two or more different kinds of elementsElectronProtonNeutronMeasurements and Measurement UnitsMeasurements consist of two parts: the number and a unit or label. Measurements are made using measuring devices. There are different systems of measurement, called metric systems. In chemistry, we use the metric system. - It is a decimal system in which larger and smaller units are related by factors of 10- Commonly used base units in the metric system:o Length = meter (m)o Volume = liter (L)o Mass = gram (g)o Time = second (s)o Temp = ˚Celsius (˚C)o Energy = calorie (cal), (a nutritional Calorie, or a Cal, is worth 1000 scientific calories)o Amount of substances = mole (mol)- Common prefixes used in metric systemo mega-; M; 1,000,000 x base unito kilo-; k; 1000 x base unito centi-; c; 1/100 x base unito milli-; m; 1/1000 x base unito miro-; µ; 1/1,000,000 x base unit- Temperature in the metric systemo Celsius and Kelvin scales are used in scientific worko Water boils = 212 ˚F, 100 ˚C, 373 Ko Water freezes = 32 ˚F, 0.00 ˚C, 273 Ko Absolute zero = -459 ˚F, -273 ˚C, 0