Document 17550588

 Dmitri Mendeleev arranged the known elements by
characteristics. He summarized his findings in the
periodic law which states:
 When the elements are arranged in order of increasing
mass, certain sets of properties recur periodically.
 The elements are arranged in increasing order
according to atomic mass.
 They are arranged in rows and columns based on
characteristics of elements.
 Broadly elements can be divided into 3 groups
 Metals: good conductors of heat and electricity, they are
malleable (can be pounded into flat sheets), they are
ductile (can be drawn out into thin wires), shiny, lose
electrons, chemically reactive.
 Examples include chromium, copper, strontium, and lead
 Nonmetals: can be solids, liquids, or gases, poor
conductors of heat and electricity, gain electrons,
undergo chemical changes.
 Examples include oxygen, carbon, sulfur, and bromine
 Metalloids: show mixed properties between metals
and nonmetals. They are called semiconductors with
intermediate conductivity.
 Examples include silicon, arsenic, and antimony
 The Metal, Metalloids, and Nonmetals are arranged in
particular portions of the Periodic Table.
 Each column of the Main group elements is called a
family or group. Each group has specific characteristics
 Noble gases- Group 8A Not reactive in most chemical
reactions, they are considered stable with no charge.
 Alkali Metals- Group 1A are all reactive metals, Some are
explosive. Have a positive 1 charge.
 Alkaline earth metals- Group 2A- Also fairly reactive,
but not as reactive as the alkali metals. Have a 2+ charge.
 Halogens- Group 7A Very reactive nonmetals. Have a
negative 1 charge as ions.
 The transition metals are in the middle of the table
and have varying charges