GEOL 103 Lecture Notes - Lecture 6: Unified Atomic Mass Unit, Atomic Number, Royal Aircraft Factory F.E.2
Document Summary
Element: a substance that consists of atoms all of which have identical characteristics. Atom: smallest part of a substance that still retains the properties of that substance. We can examine this all the way down one atom of an element and whether we have one atom of an element or billions of atoms, the properties of that element remain the same. Protons: have mass (1 atomic mass unit each). Neutrons: have mass (1 atomic mass unit each). On a periodic table, the element name is on top, then the atomic number (number of protons), then the symbol, then the atomic mass (number of protons plus neutrons). An element is de ned by the number of protons. The atomic mass of an element is simply the number of protons + neutrons. In general, there is about an equal number of protons and neutrons, but the number of neutrons can vary.
