Periodic Table History

History of the Periodic Table Dobereiner Triads of elements with shared properties Cannizzaro method for measuring atomic masses and interpreting the results of measurements Newlands arranged elements by atomic masses, properties repeated after every 8 elements → law of octaves

History of the Periodic Table Mendeleev & Meyer arranged elements according to the increase in atomic mass

History of the Periodic Table Mendeleev left spaces for undiscovered elements & predicted properties of those elements credited with discovering periodicity

History of the Periodic Table 2 Questions: Why could most elements be arranged by increasing atomic mass, but a few could not? What was the reason for chemical periodicity?

History of the Periodic Table Mosely shooting electrons at various metals to produce X-rays frequencies of the X-rays were unique to the metals assigned a whole number to each element → atomic numbers arrange elements by atomic numbers to get families with similar properties

History of the Periodic Table an arrangement of the elements in order of their atomic numbers so that elements with similar properties fall in the same column (group/family)

History of the Periodic Table Periodic Law the physical and chemical properties of elements are periodic functions of their atomic numbers

Periodic Table Information

Types of Elements

Periodic Table Information Types of elements: Metal – lustrous, good conductors, most are solids, malleable, ductile Nonmetal - poor conductors, no luster, neither malleable nor ductile, most are gases, wide variety of other physical properties Metalloid - properties of metals & non-metals

Parts of the Periodic Table

Periodic Table Information horizontal rows of elements Group (family) vertical columns of elements

Periodic Table Information Group (family) alkali metals – group 1 (except hydrogen) alkaline earth metals – group 2 transition metals – all of the d-block elements inner transition metals – all of the f-block elements metalloids – elements that touch the “staircase” halogens – group 17 noble gases – group 18 (elements with filled outer shells of electrons)