Periodic table and element structure

• Topics covered

  • Periodic Table and Element Structure
  • Elements, Compounds and Reactions
  • Newton's Second Law of Motion
  • Momentum
  • Energy
  • Conservation of Energy
  • Interaction of Forces
  • Cells (tissues, organs, and systems, cell division and reproduction)
  • Metabolism (Digestion and Gas exchange)
  • Interaction between organisms (food chains and food webs)
• Everything in the universe, including all matter on Earth, is formed from unique combinations of tiny, neutral particles called atoms
• Atoms of the same kind come together to form elements
• To this date, there are 118 elements that have been discovered
• The elements' names have been placed in a chart called the periodic table
• The placement of each element in this "warehouse" is based on the characteristics of that particular atom
• Atom


  The smallest component of an element that has the properties of that element
• Atom


  • Consists of electrons, protons, and neutrons
• Electron


  A negatively charged subatomic particle with no known substructure
• Proton


  The positively charged particle found in the center of the atom
• Neutron


  A particle in the nucleus that has a mass similar to the proton but no charge
• Isotopes


  Atoms of the same element that differ in the number of neutrons
• Bohr model


  • Concentric circles around a central nucleus, electrons travel in set energy levels
• Quantum model


  • Regions within the atom where there is a high probability of finding the electrons (electron orbitals), electrons move within the electron cloud at high speeds
• The accepted modern atomic theory states that an atom consists of a positively charged, centrally located nucleus containing protons and neutrons, and negatively charged electrons are found in the area around the nucleus in the electron cloud
• Valence electrons


  Electrons found in the outermost energy level of an atom, determine the atom's reactivity
• Dmitri Mendeleev organized the elements into a periodic table based on their physical and chemical properties
• Henry Moseley proposed organizing the elements by atomic number, which resolved anomalies in Mendeleev's table
• Periodic law


  The physical and chemical properties of the elements are periodic functions of their atomic numbers
• Classifications of elements


  • Metals
  • Nonmetals
  • Metalloids
• Metals


  • Dense, shiny solids, high melting points, malleable and ductile, good conductors of heat and electricity
• Nonmetals


  • Dull surface, poor conductors of heat and electricity, low melting points, brittle
• Metalloids


  • May be shiny or dull, can conduct heat and electricity but not as well as metals
• Main groups


  • Group 1: Alkali metals
  • Group 2: Alkaline earth metals
  • Group 17: Halogens
  • Group 18: Noble gases
• Alkali metals


  • Silver-colored, soft metals, highly reactive, have one valence electron
• Alkaline earth metals


  • Silver-colored, soft metals, slightly less reactive than alkali metals, have two valence electrons
• Halogens


  • Highly reactive nonmetals, rarely found in elemental form, have seven valence electrons
• Noble gases


  • Nonreactive gases, odorless and colorless, have a full octet of valence electrons
• Transition metals


  • Variable number of valence electrons, ductile and malleable, good conductors of heat and electricity, high density and melting/boiling points, compounds are usually colored
• Inner transition metals (lanthanides and actinides)

  • Rare earth elements, expensive to obtain, used in various modern industries and applications, most actinides are radioactive
• Periodic trends can be explained by the attraction of valence electrons to the nucleus, repulsion between electrons, and energy levels within the atom
• Atomic radius


  Measurement from the nucleus of one atom to the outermost shell of electrons
• All the actinides are radioactive, and most do not occur naturally on Earth. Instead, they can only be created in laboratories under very specific conditions, and most have incredibly short half-lives.
• Periodic Trends


  • Predict Properties with Trends
  • Characteristics can be used to determine trends
  • Trends can be explained by attraction to nucleus, repulsion of electrons, and energy levels
• Atomic radius


  Measurement from nucleus of one atom to nucleus of same type of atom it is touching, then divided in half
• Moving from left to right on periodic table

  Atomic radii decrease
• Moving down a group

  Atomic radii increase
• Ion


  Atom with a charge, determined by number of electrons gained or lost
• Cation


  Positively charged ion
• Anion


  Negatively charged ion