Periodic Table: Representation & Organization 4-Ch 1

The Periodic Classification of the Elements  The Periodic Table Periodic Classification: A way to group the elements according to certain properties Periodic Table of Elements: a visual presentation of the elements in groups according to their physical and chemical properties

Review: Physical vs Chemical Properties Physical Property: A property that can be observed or measured without changing the make-up of the matter of the object (ex: colour, odor, texture, density, melting point, boiling point) Chemical Property: Cannot be determined by simply viewing or touching the object; only becomes evident during a chemical reaction (ex: reactivity with other chemicals, flammability, heat of combustion)

How the Periodic Table is Divided/Organized Each element has its own box/square For each element: Symbol of the Element: This is universal (same for all languages) Atomic Number: always located at the top Atomic Mass: always located at the bottom Name of the Element: Written in the language of the document

First Major Division: Metals, Non-Metals & Metalloids All the elements can be placed into these three categories The “staircase” helps locate and identify the categories

Metals Location: To the LEFT of the staircase Properties: Conduct heat and electricity well Ductile (can stretch) Malleable (can bend) Usually shiny (luster) Soft Very reactive with water & acids High melting point Solid at room temperature EXCEPT for Mercury (liquid)

Non-Metals Location: To the RIGHT of the staircase EXCEPT for Hydrogen Properties: Poor conductors of heat and electricity Many are gases at room temperature No lustre Not malleable, ductile or soft

Metalloids Location: Found along the “staircase” Properties: Only 7 in total (Boron, Silicon, Germanium, Arsenic, Antimony, Tellerium, Astatine) Have some properties of metals AND some of non-metals Some are very good conductors, others are very poor – used as semiconductors in circuits and lasers

Groups of the Periodic Table All the elements found in one COLUMN (going up and down) belong to a GROUP All elements in a group have: Similar chemical properties The same number of valence electrons Groups are labeled using Roman numerals (1 = I, 2 = II) and either A or B “A” = main elements (biggest columns) “B” = transition elements (short columns) Roman numeral = number of valence electrons

Alkali Metals Location: The first column on the left of the periodic table (except Hydrogen) Properties: Soft HIGHLY reactive metals

Alkaline Earth Metals Location: The second column on the periodic table Properties: Highly malleable (soft) Reactive Burn easily in the presence of heat

Halogens Location: The second-last column on the periodic table Properties: Non-metals React easily to form compound Commonly form salts when combined with metals

Noble Gases (Inert Gases) Location: The final column of the periodic table (on the right) Properties: Very stable, do not react well Commonly found in nature Bright light is produced when electricity is passed through

The Periods of the Periodic Table Elements found in each row (going across) have the same number of shells around the nucleus The period number corresponds to the number of electron shells