Lesson 19 Periodic Table Origin and Regions Learning Targets: -         I can explain the development process for the periodic table. - I can indicate the common information found on most periodic tables. -         I can name regions of the periodic table.   PA Science and Technology Standards: 3.1.10.C; 3.4.10.A; 3.4.12.A

I. Dmitri Mendeleev invented the periodic table. a I. Dmitri Mendeleev invented the periodic table a.       Different kinds of elements have similar properties. b.      Before 1871, it was not known just how regularly these properties varied. c.       Mendeleev wrote down the elements that were known at the time, and shuffled them around. d.      He found that when you put them in numeric order by mass, and similar properties together, they formed columns, or “groups” e.       There were several gaps in the table, and Mendeleev predicted properties of those elements with a decent amount of accuracy.

II. The modern periodic table is based on the periodic law. a II.  The modern periodic table is based on the periodic law. a.       Mendeleev’s table had some other problems, such as some elements not seeming to fit into the columns that they fell in. b.      Henry Mosley, 40 years later, rearranged the table by atomic number, rather than atomic mass. The irregularities disappeared. c.       The current periodic table is based on the periodic law.                       i.      Periodic Law - The physical and chemical properties of the elements are periodic functions of their atomic numbers                       ii.      This generated a table of the modern shape, instead of the simple rectangle that Mendeleev created.

III.           You can find the following information on most periodic tables. a.       Name/Symbol b.      Atomic Number c.       Atomic Mass

IV. Regions of the Periodic Table. a IV.       Regions of the Periodic Table a.       The periodic table contains regions of similar elements                i.      Metals 1.      Everything to the left of the dividing line, except for hydrogen 2.      Form the largest part of the table 3.      Generally lustrous, malleable, and ductile 4.      Excellent conductors of heat and electricity 5.      Generally have positive oxidation numbers (or charges)

ii. Non-Metals. 1. Everything to the right of the dividing line,                    ii. Non-Metals 1.      Everything to the right of the dividing line, except for group 18 2.      Generally poor conductors of heat and electricity 3.      Most are gases or brittle solids at room temperature 4.      Generally have negative oxidation numbers (or charges)

iii. Metalloids. 1. All of the elements which are along the                   iii.      Metalloids 1.      All of the elements which are along the dividing line, as in touching on one or more sides (not just at a corner). 2.      Some properties of both metals and non- metals 3.      Often used for semiconductors – computers 4.      6 elements, B, Si, Ge, As, Sb, Te, are usually considered metalloids. Depending on what properties are being looked for, some others may or may not be considered to be metalloids.

iv. Noble Gases. 1. Group 18. 2. All are nonreactive gases ii                   iv.      Noble Gases 1.      Group 18 2.      All are nonreactive gases             ii.      In the following space, draw the periodic table, and show the four regions discussed above.