ioc lec prelims

• periodic table


  Arranges elements in rows (periods), and columns (groups) according to increasing atomic number.
• aristotle


  He proposed that there are only (4) four elements: Fire, Water, Air, and Earth
• in the year 1700, 14 elements were known
• antoine lavoisier (1789)


  Wrote the first extensive list of 33 elements
• johann dobereiner

  • A German Chemist.
  • Arranged elements by increasing atomic weights.
  • Discovered that in a group of three, the average atomic mass of the third element is equal to the atomic mass of the second element.
  • Created the Law of Triads.
• john newland

  • English Chemist.
  • Arranged the known 62 elements from, lightest to heaviest based on increasing atomic weights.
  • Noticed that every 8th element had a similar chemical and physical properties.
  • First to formulate the concept of periodicity in the property of chemical elements.
• dmitri mendeleev

  • Organized elements by atomic mass and created a table to help students.
  • Created first widely known periodic tables.
• dmitri mendeleev


  he is the father of the modern periodic table
• henry moseley


  he arranged elements by atomic number.

  Gave rise to a New Periodic Law: “Properties of elements are periodic functions of their atomic number.”
• glenn searborg, he discovered 8 new elements.

  Only living person from which an element was named: Seaborgium
• Elements, names, and symbols are given on the periodic table.
• 118 elements have been identified.

  82 elements occur naturally on earth.

  36 of them are made by scientists
• periods

  periodic terminology: Horizontal rows (left to right)
• group/family

  periodic terminology:vertical rows (up to down)
• metals


  periodic terminology: Located on the leftmost part
• metals


  Usually exist as shiny solids

  Tend to lose electrons to form + ions (cations)

  Shiny, Malleable, and Ductile

  Good conductors of heat and electricity.

  Reacts with acid
• non metals


  periodic terminology:Located on the right part
• non metals


  Do not have a shiny appearance

  Tend to gain electrons to form - ions (anions)

  Dull and brittle

  Poor conductors of heat and electricity.

  Good insulators