The Periodic Table

The Father of the Periodic Table Dimitri 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

A Correction to the Periodic Table Henry Moseley later discovered that the periodic nature of the elements was associated with atomic number, not atomic mass The current table is arranged by atomic number.

Column = Group or Family 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 Hydrogen 1.008 Atomic Number = # of protons # of electrons Elemental Symbol Atomic Mass = # of protons + neutrons

Organization of the Periodic Table Organized by Atomic Number Metals Non Metals Metalloids Groups (Columns/Families) Periods (Rows)

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

GROUPS/Family Elements in the same group behave in similar ways Each column is called a “group/Family” Groups have SIMILAR PROPERTIES Elements in the same group behave in similar ways The group that an element is in tells you how many valence electrons it has. This means that they have the same number of electrons in the outermost shell.

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

The Groups of the Periodic Table Groups 3-12: Transition Metals Found freely and in compounds in nature Charge is usually 2 but can vary Usually 2 valence electrons Group 13: Boron Family Charge is 3 3 valence electrons

The Groups of the Periodic Table Group 14: The Carbon Family Contains elements that can form unusual bonds (carbon and silicon) Charge is +4 or -4 contains 4 valence electrons Group 15: The Nitrogen Family Charge is -3 contains 5 valence electrons

The Groups of the Periodic Table Group 16: The Oxygen Family Also known as the chalcogens Charge is -2 6 valence electrons Group 17: The Halogens Most reactive nonmetals charge is -1 7 valence electrons Group 18: The Noble Gases (The Inert Gases) Nonreactive Charge is 0 2 or 8 valence electrons

Periods (Rows) The period an element is in indicates how many “shells” it has around it.

Special Rows on the PT—Transition Lanthanides Actinides *The Lanthanides & Actinides together are called the Inner Transition Elements.