CHEM 1111 Lecture Notes - Lecture 2: Cathode Ray Tube, Subatomic Particle, Henri Becquerel
Document Summary
Discovery of the electron: j. j. thomson- experimented with cathode ray tubes and calculated the charge-to-mass ratio of the cathode ray particles (1. 759 x 1011 c/kg, cathode ray tube- a glass vacuum tube that contains two metal electrodes. When there is high voltage, a visible beam (cathode ray) appeared between them. Subatomic particles and atomic structure: wilhelm rontgen- discovered x-rays. These are slightly larger than protons: electrons- negatively charged and distributed around the nucleus. Properties of subatomic particles: proton- mass = 1. 0073 amu, neutron- mass =1. 0087 amu, electron- mass = . 00055 amu. Atomic number, mass number and isotopes: all atoms can be identified by the number of protons and neutrons they contain, atomic number (z)- the number of protons in the nucleus. Protons and neutrons are collectively referred to as nucleons: chemical symbols- an abbreviation used to refer to an element or an atom of an element. Ex- a neutral sodium atom (z = 11) has 11 electrons.
