CHEM 101 Lecture Notes - Lecture 2: Periodic Trends, Natural Abundance, Deuterium
Document Summary
**know the name and symbol for the first 20 elements on the periodic table** Matter- anything that has mass and occupies a space (volume) Macroscopically can classify matter: pure compounds. Compounds (millions)- more than one element in definite proportion (ratio: mixtures- have more than one pure compound. Microscopically- matter is discrete (it is made up of atoms) Protons: charge: +1, relative mass: 1 amu (atomic mass unit) Neutrons: charge: 0, relative mass: 1 amu. Electrons: charge: -1, relative mass: 0 amu. In neutral atoms, the number of protons equals the number of electrons: 91 different elements in nature that make up the universe. Nucleus: made up of protons and neutrons: protons. The number of protons in an atom is unique to an element. When the number of protons changes, the element will change. Mass of proton: 1 amu: neutrons. Unlike protons, the number of neutrons in an atom of an element can vary.
