2. T HE P ERIODIC T ABLE

3. Groups are the vertical columns in the periodic table. The group number is located above each column. Periods are the horizonta l rows. The number is located on the left of each row. Groups are the most common way of classifying elements, but there are some regions of the periodic table where the horizontal trends and similarities in properties are more significant than vertical group trends

4. M ETALS  Good conductors of heat and electrical conductors  Malleable  Shiny  Have luster  Ductile  Mostly solids at room temperature  Metals are located on the left side and the middle of the periodic table.

5. N ONMETALS  Poor thermal conductors  Poor electrical conductors  Brittle Solids  Little or no metallic luster  The nonmetals are located on the upper right side of the periodic table.  Nonmetals are separated from metals by a line that cuts diagonally through the periodic table.

6. L ANTHANIDES  Silvery metals that tarnish easily  Relatively soft metals, with high melting and boiling points  React to form many different compounds  Lanthanides are in the top row of the 2 rows located underneath the main body of the periodic table.

7. A CTINIDES  Radioactive with positively charged ions  Combine directly with most nonmetals  React with boiling water or dilute acid to release hydrogen gas  Tarnish readily in air  Actinides are in the row below the Lanthanides.

8. N OBLE G ASES  Fairly nonreactive because they have little tendency to gain or lose electrons  Complete valence shell  High ionizatoin energies  Very low electronegativities  Low boiling points, all gases at room temperature  Noble gases are located in Group 18, on the far right of the periodic table