2.3: the periodic table

groups in the periodic table

• metals
    * conductors (to varying degrees)
    * lose electrons
    * malleable and ductile (flexible)
    * shiny/lustrous
• nonmetals
    * nonconductors
    * gain electrons
    * brittle (not malleable or ductile)
    * dull in texture/appearance
• metalloids/semi-conductors
    * bridge metals and non-metals, have qualities of both

metal groups

• alkali metals
    * have one valence electron (electron in the highest occupied energy level)
    * most reactive metal group
• alkaline earth metals
    * 2 valence electrons
    * less reactive than alkali metals
    * 2nd most reactive group
• transition metals
    * multiple charges on ions
    * some references refer to these elements as “post-transition metals”
    * don’t behave consistently

nonmetal groups

• halogens
    * 7 valence electrons
    * most reactive nonmetal group
• noble gases
    * 8 valence electrons (highest occupied energy level is full)
    * most stable group

the periodic table

• periodic table: a systematic organization of the elements
• elements are arranged in order of atomic number
• the rows of the periodic table (left to right) are called periods
• the columns of the periodic table (top to bottom) are called groups or families
• elements in the same group have similar properties
• periodicity
• periodic = cyclical
• there is a repeating pattern of reactivities and other properties as we move across the periodic table
• metals are on the left side of the periodic table, whereas non-metals are on the right side of the table (except for Hydrogen). metalloids are near the right side but not on the far right.