ACA Grade 8 Science
  • Home
  • Scientific Method
  • Chemistry
  • Physics
  • Ecology
  • Earth's Atmosphere
  • Science Fair/ Science Olympics
  • Cells & Systems

Periodic Table - Mendeleev Discovery     Lesson 3.2

Picture
Picture
How did Mendeleev discover the pattern that led to the periodic table?
Dmitri Mendeleev
  • In 1869, the Russian scientist Dmitri Mendeleev discovered a set of patterns in the properties of the elements.
 
 
 










Pattern of Properties
  • He noticed that a pattern of properties appeared when he arranged the elements in order of increasing atomic mass.
 
 
 











Atomic Mass
  • The atomic mass of an element is the average mass of all the isotopes of that element.
 
 
 






Periodic Table & Undiscovered Elements
  • Mendeleev published the first periodic table.
  • In the periodic table, the properties of the elements repeat in each period, or row, of the table.
  • Mendeleev left three blank spaces in the table.
  • He predicted that these spaces would be filled by elements that had not yet been discovered.
 




 
 

Predicting Properties
  • He even predicted the properties of those elements.
  • Those elements were soon discovered. Their properties are close to those predicted by Mendeleev.
 
 
 

Updated Periodic Table
  • The periodic table has been updated since Mendeleev's time as scientists discovered new elements.
 
 
 









Protons & Atomic Number
  • After protons were discovered, elements were rearranged according to atomic number.
  • Some elements changed positions and the patterns of properties became more regular.
Picture
Picture
Picture
Picture
Picture
Picture
Picture

Mendeleev Discovery
Element Data
Periodic Table Organization

Back
Powered by Create your own unique website with customizable templates.