CH 110 Lecture Notes - Lecture 2: Unified Atomic Mass Unit, Relative Atomic Mass, Mass Number

• School: University of Hartford
• Department: Chemistry - A&S
• Course: CH 110
• Professor: Raynaldo Scarlett

Document Summary

Democritus and early greeks - tiny non divsiable particles - atomos. Law of conservation of mass (dalton"s postulate 3) Number of particles = number particles after reaction. N2 (g) + o2 (g) 2no (g) O2 = 2 (16g) = 32g 60g. Cathode - ray tube - uses perpendicular magnetic and electric field to direct electrons moving b/w cathode (-) and anode (+) Rutherford - used alpha (+ charged) particles to study deflection upon a gold film surface. Positively charged proton and identified positive nucleus - contains protons and neutrons. Every atom has equal number of electrons and protons so atoms do not have a charge diameter of atom 1 x 10-10 meter to 5 x 10-10 meter. Mass number - mass number equal to sum of protons and neutrons. Atomic number - equal to number of protons or electrons. Extremely small use unit of amu (atomic mass unit) Isotopes - have the same atomic number but different mass number.