The Modern

Periodic Table

In the 1860s, Russian Dmitri Mendeleev developed an approach for organizing the elements while playing the card game solitaire.

Mendeleev's Periodic Table

Mendeleev made a “deck of cards” of the elements, listing an element’s name, mass, and properties on each card. When Mendeleev lined up the cards in order of increasing mass, a pattern emerged. The key was to break the elements into rows.

Mendeleev's Periodic Table

Arrangement of the Periodic Table

• Today, elements are arranged by increasing atomic number (number of protons & electrons).

• Each row in the table of elements is a period. (Period # = # of energy levels)

• Each column in the periodic table is called a group. (Group # = # of valence electrons)

– similar electron configurations

– similar chemical properties

Classes of Elements• Three different ways to classify elements:

• State of Matter (Look @ the color the element’s symbol is written in)

• solid—black symbol

• liquid—purple symbol

• gas—red symbol

• Occurrence in nature• elements that do not occur naturally—white symbol.

• General properties• metal—blue background

• nonmetal—yellow background

• metalloid—green background

Metals• majority of the elements on the

periodic table

• good conductors of electric current and heat• Except for mercury, metals are solids at room

temperature.

• Most metals are malleable.

• Many metals are ductile; that is, they can be drawn into thin wires.

Transition Metals•metals in groups 3 through

12

• form a bridge between the elements on the left and right sides of the table

Nonmetals• generally have properties

opposite to those of metals• are poor conductors of heat and electric

current.

• Nonmetals have low boiling points–many nonmetals are gases at room temperature.

• Nonmetals that are solids at room temperature tend to be brittle.

Metalloids• Located between metals and nonmetals

• properties that fall between those of metals and nonmetals– a metalloid’s ability to conduct electric current

varies with temperature

• Ex: Silicon (Si) and germanium (Ge) are good insulators at low temperatures and good conductors at high temperatures.

Questions…(Answer on your notes)

1. What are the three categories we use to classify elements on the periodic table?

2. What is a row of the periodic table called?

3. What is a column called?

4. What is the group name for elements in groups 3 through 12?

5. What are the differences between metals and nonmetals?