In 1819 he created the first accepted version of the periodic table.
He grouped elements according to their atomic mass, and as he did, he found that the families had similar chemical properties.
Three Catagories of periodic table
Metals, Non-Metals, Metalloids.
(left side) They are good conductors of heat and electricity. They are also ductile and malleable.
(right side) They are poor conductors of heat and electricity. They are not ductile and malleable.
(between both) They have properties of both metals and non-metals. They conduct heat and electricity better than non-metals but not as well as metals.
All members have the same number of valence electrons. Have similar physical and chemical properties.
The first element is always an extremely active solid. The last is always an inactive gas. Do not have similar properties.
Electrons in outer shell.
Only non-metal that acts like a metal
Most reactive (1 valence electron
Alkaline Earth Metals
Less reactive than alkali metals. Never found uncombined in nature. Have 2 valence electrons
Less reactive than alkaline earth metals. Good conductors of heat and electricity.
3 Valence electrons
4 Valence electrons. "Basis of life"
5 Valence electrons. They share electrons when they bond.
6 Valence electrons. They share electrons when they form compounds.
7 Valence electrons. Most active non-metals.
8 Valence electrons. Unreactive.