CHEM 101 Lecture Notes - Lecture 5: Subatomic Particle, Unified Atomic Mass Unit, Atomic Number

• School: Binghamton University
• Department: Chemistry
• Course: CHEM 101
• Professor: Steven Boyer

Document Summary

Subatomic particle: a very small particle that is a building block for atoms. Equal in magnitude to the electron"s negative charge. Mass is completely dependent on protons and neutrons. Atomic mass unit (amu) = mass of a proton/neutron. 1 amu is equal to 1/12 the mass of the carbon-12 atom. Internal structure of an atom: nucleus. Small compared to the overall size of the atom. Extremely dense; accounts for almost all of the atom"s mass. An atom as a whole is electrically neutral (no net electrical charge) Complete chemical notation (periodic table is labeled in reverse) Element: a pure substance in which all atoms present have the same atomic number, all atoms with the same atomic number have the same chemical properties and are atoms of the same element. Atoms of an element that have the same number of protons and a different number of neutrons. Show almost identical chemical properties; chemistry of an atom is due to its electrons.