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• Dmitrii Mendeleev (1869) – arranged elements by atomic mass• Elements arranged in columns had similar properties• This was not perfect

• many gaps• some elements out of place (ie. Nickel and Cobalt)

• Henry Moseley (1913) proved the relationship between atomic number and the number of protons in the nucleus

• – led to the development of the current Periodic Table

• The Periodic Law states:• When elements are arranged in order of increasing atomic number,

their physical and chemical properties show a periodic pattern.

Origins of the Periodic Table

• Groups – (family) Vertical columns, 1 through 18• Pertains to the Valence Electrons (electrons in outer shell)

• Periods – the horizontal rows, 1 through 7• Pertains to Energy levels of electrons

• Question: Which element is in group 14 and period 4?

Three classes of elements:MetalsNonmetalsMetalloids (aka Semi-Metals)

Organization of the Periodic Table

Germanium

Characteristics●Left side of the table●most abundant (2/3rds of the table)●Malleable - can pound into sheets●Ductile - can draw into wires●Luster – shiny●Good conductors of heat & electricity●high melting point

●except mercury which is liquid at room temperature●Metals lose electrons to become positive ions called cations●more reactive going down and left

●The most reactive metal ____________________

Metals

Francium

Characteristics●Right side of the table●Soft or brittle●Dull●Low melting points, many are gases, few are solid

●Only one liquid nonmetal: bromine●Gain electrons to become negative ions called anions●more reactive going up and right (Noble gases excluded)

• Most reactive nonmetal _______________

●Metalloids (semi-metals) - found in between metals and nonmetals (“along the staircase”)●Properties can be metallic or nonmetallic●depending on conditions

Nonmetals

Fluorine

Periodic Table Activity

1. On your Periodic Table, identify and color the metals

2. Identify and color(use 1 color for all) the MetalloidsBoron Silicon GermaniumArsenic Antimony Tellurium Astatine

3. Identify and color the nonmetals

4. Put a dark outline around the two liquid elements, mercury and bromine