5.2 The Periodic Table

Organizing the periodic table… Timeline of Element Discoveries By 1750 there were only 17 elements identified In 1860 Dmitri Mendeleev, Russian chemist, organized the elements in rows of increasing mass number so that elements with similar properties were in the same column

Organizing the Periodic Table… Mendeleev noticed holes in his periodic table and predicted the holes would be filled as more elements were discovered. Mendeleev could also predict the properties of these missing elements because his periodic table arranged elements with the same properties together.

Mendeleev

Modern Periodic Law The Periodic table is arranged with increasing atomic number (number of protons). Periods – a row on the periodic table Groups or Families – a column on the periodic table

Periods Families The periodic table has _______ periods. Elements in similar groups or families have similar properties This pattern of the periodic properties is called the periodic law

Atomic Weight Atomic Weight – the average mass of all the isotopes found in nature.

Classes of Elements Metals Left side of the periodic table Good conductors Mostly solid at room temp Most are malleable and ductile Most are reactive

Classes of Elements Nonmetals Right side of the periodic table Poor conductors Most are gases and liquids at room temperature Can be very reactive or very unreactive

Classes of Elements Metalloids Elements with properties that are in between metals and nonmetals Germanium Boron Silicon Antimony Tellurium

Label Your Periodic Table! Include, Periods, Groups, Metals, Nonmetals, Metalloids