2.7 an Introduction to the Periodic Table Periodic Table

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2.7 An Introduction to the Periodic Table Periodic Table

Dmitri Mendeleev (1834-1907)

On the periodic table, • elements are arranged according to similar properties. • groups contain elements with similar properties in vertical columns. • periods are horizontal rows of elements.

Group Numbers • use the letter A for the representative elements (1A to 8A) and the letter B for the transition elements. • also use numbers 1-18 to the columns from left to right.

Several groups of representative elements are known by common names.

Group 1A(1), the alkali metals, includes lithium, sodium, and potassium.

Group 7A(17) the halogens, includes chlorine, bromine, and iodine.

Identify the element described by the following.

A. Group 7A(17), Period 4 1) Br 2) Cl 3) Mn

B. Group 2A(2), Period 3 1) beryllium 2) boron 3) magnesium

C. Group 5A(15), Period 2 1) phosphorus 2) arsenic 3) nitrogen

A. Group 7A (17), Period 4 1) Br B. Group 2A (2), Period 3 3) magnesium C. Group 5A(15), Period 2 3) nitrogen

The heavy zigzag line separates metals and nonmetals. • Metals are located to the left. • Nonmetals are located to the right. • Metalloids are located along the heavy zigzag line between the metals and nonmetals.

Metals • are shiny and ductile. • are good conductors of heat and electricity. Nonmetals • are dull, brittle, and poor conductors. • are good insulators. Metalloids • are better conductors than nonmetals, but not as good as metals. • are used as semiconductors and insulators.

Identify each of the following elements as 1) metal 2) nonmetal 3) metalloid

A. sodium ____ B. chlorine ____ C. silicon ____ D. iron ____ E. carbon ____

Identify each of the following elements as 1) metal 2) nonmetal 3) metalloid

A. sodium 1 metal B. chlorine 2 nonmetal C. silicon 3 metalloid D. iron 1 metal E. carbon 2 nonmetal