CHEM 1311 Lecture Notes - Lecture 3: Dmitri Mendeleev, Julius Lothar Meyer, Alkali Metal
Chapter 4: Electron Configuration and
the Periodic Table
Focus of this section: Development of Periodic Table
Modern Periodic Table
Periodic Trends
Development of Periodic Table
• Nineteenth century—arrangements based on atomic mass
-- Dmitri Mendeleev & Lothar Meyer (1864 to 1869):
= independently proposed idea of periodicity
(recurrence of properties)
= Grouped elements (66) according to properties
= Predicted properties for elements not yet
discovered (e.g. Gallium)
= could not explain inconsistencies and gaps
Modern Periodic Table
• modern Periodic Table = based on atomic number
-- cleared up discrepancies, removed gaps
-- arranged according to e– configuration
• periods = horizontal rows
families (groups) = vertical columns
-- elements in the same family have similar chemical
and physical properties
• Metals: good conductors of heat and electricity (majority of
elements on the table-located to the left of the stair step)
-- Shiny, lustrous, malleable, ductile
• Nonmetals: nonconductors (located in upper right corner)
-- Vary in color, not shiny -- Brittle
-- Poor conductors
• Metalloids: in between metals and nonmetals (those that lie
along the separation line)
• Main group elements (representative elements): Group
1A to 7A
• Group 1A: Alkali metals: ns1
-- form basic solutions when reacted with water
• Group 2A: Alkali earth metals: ns2
-- found in minerals in ground
• Group 8A: Noble gases: ns2 np6 (He = 1s2)
-- filled shell
-- relatively unreactive
• Group 7A: Halogens: ns2 np5
-- obtained from the sea
• Group 6A: Chalcogens: ns2 np4
Document Summary
Chapter 4: electron configuration and the periodic table. Focus of this section: development of periodic table. Development of periodic table: nineteenth century arrangements based on atomic mass. - dmitri mendeleev & lothar meyer (1864 to 1869): = independently proposed idea of periodicity (recurrence of properties) = predicted properties for elements not yet discovered (e. g. gallium) Modern periodic table: modern periodic table = based on atomic number, periods = horizontal rows families (groups) = vertical columns. - elements in the same family have similar chemical and physical properties: metals: good conductors of heat and electricity (majority of elements on the table-located to the left of the stair step) - shiny, lustrous, malleable, ductile: nonmetals: nonconductors (located in upper right corner) - brittle: metalloids: in between metals and nonmetals (those that lie, main group elements (representative elements): group along the separation line) - form basic solutions when reacted with water.
