The Periodic Table Textbook Pages: 22-30

The Development of The Periodic Table Dmitri Mendeleev ( ) Russian Chemist Developed table according to increasing atomic masses Similar elements arranged in same column “Father” of the Periodic Table

The Modern Periodic Table Periodic Law: When elements are arranged by atomic number, their chemical and physical properties recur periodically. Describes the repeating nature of the properties of the elements

T.P.S. Question Think Pair Share What else can you tell me about the characteristics of the modern Periodic Table?

The Modern Periodic Table The Periodic Table is split up into: 1. Groups 2. Periods Group: Vertical column in the Periodic Table Same number of valence electrons Similar chemical and physical properties Family Period: Horizontal row in the Periodic Table Atomic number increases from left to right Period number is number of electron shells occupied by electrons As go across period, outer electron shell is being filled Energy level 34

The Modern Periodic Table Group 1: Alkali Metals Very reactive metals Group 2: Alkaline Earth Metals Groups 3-11: Transition Metals Metalloids Properties between metals and non-metals Group 17: Halogens Reactive non-metals Group 18: Noble Gases Completely unreactive

Periodic Trends  Atomic Radius  Ionization Energy  Electron Affinity  Electronegativity

Periodic Trends Definitions  Atomic Radius The distance from the center (nucleus) of an atom to the boundary within which the electrons spend 90% of their time (outer perimeter)  Ionization Energy The amount of energy required to remove the outermost electron from an atoms or ion in the gaseous state (eliminate effect of nearby atoms) Equations: A (g) + energy  A + (g) + e− (first ionization) A + (g) + energy  A 2+ (g) + e− (second ionization) ***Requires more energy  Electron Affinity The energy absorbed or released when an electron is added to a neutral atom  Electronegativity An indicator of the relative ability of an atom to attract shared electrons