 Russian Chemist Dmitri Mendeleev produced the first periodic table of elements  He arranged them in order of increasing atomic mass and noticed a periodic repetition of their properties  Mendeleev knew he was not completely correct with his table and left blank spots showing places where he thought an undiscovered element existed

 The Table of Elements is a display of the chemical elements organized on the basis of their properties and presented in increasing atomic number.

 When elements are arranged in order of increasing atomic number, their physical and chemical properties show a periodic pattern

 Has 109 squares, each representing an element  Squares aligned in vertical columns called groups › Elements in these groups have similar properties  Horizontal groups are called periods  The Periodic table has 7 periods and 18 labeled groups

 Some groups are given family names  Groups on at the far left and right of the periodic table are very similar within their group and are commonly referred to by their family names  Examples are the alkali metals, alkaline earth metals, halogens, and the noble gases

 Metals- on the left side of the table › share many properties and are characterized by their luster or shine › Good conductors of heat and electricity › Typically solids and room temperature › Malleable and ductile

 Nonmetals- right side of the table except hydrogen › Do not have metallic luster › Poor conductors of heat and electricity › Neither malleable or ductile › Many are gases at room temperature and others are solids

 Metalloids- have properties of metals and nonmetals  Located in between metals and nonmetals in a staircase pattern

 Atomic Radius- distance from the center of an atom’s nucleus to its outermost electron  If you go down each group on the periodic table, the atomic radius increases  If you left to right across each period, the atomic radius decreases

 The energy needed to remove one of its electrons  Think of it as how strongly an atom holds onto its electrons  High ionization energy means atoms hold onto their electrons very tightly  Ionization energy decreases as you go down a group  Increases as you move from left to right across a period

 Ability to attract electrons in a chemical bond  Increase as you move left to right across a period and decrease as you move down a group