Atomic structure and the periodic table

• Proton


  A positively charged particle found in the nucleus of an atom, with a mass number equal to the number of protons.
• Neutron


  A particle found in the nucleus of an atom, with no charge, and a mass slightly larger than a proton.
• Electron


  A negatively charged particle found in the outermost energy level of an atom, with a very small mass.
• Atomic number


  The number of protons in an atom's nucleus, defining the element of an atom.
• Nucleus


  The central part of an atom, where protons and neutrons are found.
• Isotopes


  Atoms of the same element with the same number of protons (atomic number) but different numbers of neutrons.
• Ions


  Atoms that have gained or lost electrons to form ions with positive or negative charges.
• Periods


  Rows in the periodic table where elements with similar trends in properties are grouped together.
• Groups


  Columns in the periodic table where elements with similar chemical properties are grouped together.
• Metals


  Elements that are typically shiny, malleable, and good conductors of electricity.
• Non-metals


  Elements that are typically dull, brittle, and poor conductors of electricity.
• Metallic character


  Tendency of an element to exhibit metallic properties.
• Non-metallic character


  Tendency of an element to exhibit non-metallic properties.
• Chemical symbol


  One- or two-letter abbreviation for an element's name.
• Group numbers


  Numbers assigned to groups in the periodic table.
• Period numbers


  Numbers assigned to periods in the periodic table.