The Periodic Table

The Father of the Periodic Table—Dmitri Mendeleev Mendeleev was the first scientist to notice the relationship between the elements Arranged his periodic table by atomic mass Said properties of unknown elements could be predicted by the properties of elements around the missing element Moseley later discovered that the periodic nature of the elements was associated with atomic number, not atomic mass

The Periodic Table Column = Group or Family 18 columns on the Periodic Table Row = Period 7 rows on the Periodic Table

What does the information in the box tell me? 1 H 1.008 Atomic Number = # of protons Elemental Symbol Atomic Mass = # of protons plus neutrons

Metals, Nonmetals, and Semi-metals Only nonmetal on the metal side Nonmetals are on the right of the stair-step Metals are to the left of the stair- step Semi-metals, “metalloids,” touch the stair-step

The Groups of the Periodic Table Group 1: The Alkali Metals Most reactive metals on the PT Rarely found free in nature 1 valence electron Group 2: The Alkaline Earth Metals Still quite reactive 2 valence electrons

T he Groups of the Periodic Table Groups 3-12: Transition Metals Found freely and in compounds in nature Usually 2 valence electrons Group 13: Boron Family 3 valence electrons

The Groups of the Periodic Table Group 14: The Carbon Family Contains elements that can form unusual bonds (carbon and silicon) 4 valence electrons Group 15: The Nitrogen Family 5 valence electrons

The Groups of the Periodic Table Group 16: The Oxygen Family Also known as the chalcogens 6 valence electrons Group 17: The Halogens Most reactive nonmetals 7 valence electrons Group 18: The Noble Gases (The Inert Gases) Nonreactive 8 valence electrons

Special Rows on the PT Lanthanides Actinides

How Are Elements Classified? The elements are classified into three groups. Most elements are metals, elements that are shiny and conduct heat and electricity well. Nonmetals, all except hydrogen of which are found on the right side of the periodic table, may be solids, liquids, or gases at room temperature. Between these groupings are semiconductors, elements that can conduct electricity under certain conditions.

How Are Elements Classified? Chapter 4 How Are Elements Classified? The periodic table below shows the distribution of metal, nonmetals, and semiconductors in the periodic table.

Chapter 4 Metals The alkali metals, found in Group 1 of the periodic table, are very reactive. The alkaline-earth metals, which include calcium, are found in Group 2 of the periodic table, and are somewhat less reactive than the alkali metals. The transition metals, such as gold, iron, and mercury, occupy Groups 3–12 of the periodic table.

Nonmetals Carbon is found in three different forms and can form many compounds. Nonmetals and their compounds are plentiful on Earth. Halogens, such as chlorine, are located in Group 17 of the periodic table. Noble gases, such as neon, make up Group 18 of the periodic table. They are unreactive.

Nonmetals Silicon is the most familiar semiconductor. Chapter 4 Semiconductors are intermediate conductors of heat and electricity. Silicon is the most familiar semiconductor. Silicon is an important part of computer chips, as well as other semiconductor devices such as transistors, LED display screens, and solar cells.