CCL 11101st Edition Lecture 2Outline of Last Lecture I. Some Basic DefinitionsII. Properties and Classifications of MatterIII. MeasurementsIV. Significant DigitsV. RoundingOutline of Current Lecture I. Some Important PeopleII. Experiments/LawsCurrent LectureI. Some Important People- Empedocles (495-435 BC)o Said that there were four fundamental substances: air, earth, fire, water- Democritus (460-370 BC)o Matter is particulate o Atom from Greek word atomos=indivisible- John Dalton (1766-1844)o Dalton’s Atomic Theory (1803-1807) This theory was a major advancement in what today’s atom looks likeo His theory stated that:o 1. All matter consists of tiny indivisible atomso 2. Atoms of an element are identical, but different from other elementso 3. Atoms of one element cannot be converted into another elemento 4. Compounds result from chemical combinations of different elements- JJ Thompson (1856-1940)o Further experimented with cathode raysThese 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.o Discovered electrons- Robert Milikan (1868-1953)o “Oil drop” experimento Caused oil drops to become charged and observed behavior, led to charge of electron (1.602x10^-19)o Computed electron mass (9.1x10^-28)- Ernest Rutherford (1871-1937)o Discovered the nature of radioactivityo Explained the phenomenon of radioactivity discovered by Becquerel in 1896 (emission from uranium compounds)o Alpha rays, gamma rays, beta raysII. Experiments/Laws- Three Classical laws (hint: these might be on an exam)o 1. Law of conservation of mass Can’t make or destroy mattero 2. Law of constant composition In a given compound, relative numbers and atoms are constanto 3. Law of multiple proportions ratio of mass must be integers/whole numbers; atoms go together in individual units- Experiments with cathode rayso Cathode rays are independent of the electrode materialo Cathode rays are streams of negatively charged particles- Thomson’s “Plum Pudding” modelo We can think of this like a chocolate chip cookie with an evenly distributed mass and positive charge (cookie as an entirety), and smallembedded negative particles (the chocolate chips)- Gold Foil Experimento Disproved plum pudding modelo Studies angles of alpha particles that were scattered after passing through thin gold foil- Rutherford’s Nuclear Atomo Small, very dense, positive nucleuso Surrounded by negative electronso Thomson discovered electronso Rutherford discovered protonso Chadwick discovered