Module 2.6 The Periodic Table - Portage Gen Chem 103

Groups

• Vertical columns

Periods

• Rows

Who discovered similar relationships among the properties in the 1800s?

• Dimitri Mendeleev and Lothar Meyer
• How did they predict the organization?
  • increasing mass
    • This is wrong
• How did Mendeleev one-up Meyer?
  • He used his observation to predict undiscovered elements

What became apparent during the 20th century?

• Periodic relationship involved atomic numbers rather than masses

What is the modern statement of the Periodic Law*?

• ”The properties of the elements are periodic functions of their atomic numbers”

How does the modern periodic table arrange their elements?

• In increasing order of atomic numbers and groups atoms w/similar properties in the same vertical (groups, rows) column

What does each box represent?

• Element
• Atomic number (Z)
• Symbol
• Average atomic mass
• Name

What is the name for horizontal and vertical positions?

• Periods or series (horizontal)
• Groups (vertical)
  • labeled as numbers 1-18

Which parts of two rows are written below main table?

• Lanthinides and actinides

What else did Mendeleev predict to complete the table?

• That there were more elements below Manganese in Group 7
• Who solved the puzzle?
  • Henry Moseley, then Ida Tacke and Walter Noddack

How was the Germans’ method different than everyone else’s in finding the missing pieces?

• They didn’t just focus on Manganese exclusively, they also incorporated adjacent elements 43 and 75

What was the last natural elements to be discovered?

• Rhenium (stable)
• Francium (unstable)

What are the large classes?

• Metals (shiny, malleable, good conductors, shaded blue)
• Nonmetals (dull, poor conductors, orange)
• Metalloids (ok conductors, some properties of both, gold)