The Periodic Table MAIN IDEA: Atoms of elements that are in the same group on the periodic table have similar physical and chemical properties.

Just like that spot on a map can tell you information about that location, the position of an element on the periodic table can help you predict some of the elements properties.

Element -is a pure substance made up of only one type of atom - are the building blocks of all matter -there are currently 118 known elements represented by the periodic table - Some are found in nature and others are created in laboratories. - Each little block represents one element

Periodic Table Organization -Russian chemist Dmitiri Mendeleev decided to arrange the elements in order of increasing atomic weight in the late 1800. -While doing this, he also organized them so elements with similar characteristics were grouped together. - Dmitiri left blank spots for elements that had not been discovered yet. -He was able to predict undiscovered elements! We still use this organization today but we have elements in order of increasing atomic number.

The Atom and the Periodic Table The modern periodic table consists of boxes, each contain information such as element name, symbol, atomic number, and atomic mass. What is the atomic mass of Helium? What is the atomic number of Helium? What is the symbol of Helium? Look at your periodic table: What is the atomic mass of Oxygen?

Remember: Elements on the periodic table are organized based on similarities in their physical and chemical properties. Periods & Groups The horizontal rows of elements in the periodic table are called periods. The atomic number increases across the period. Periods are numbered 1-7. Label the periods 1-7 on your blank periodic table. The vertical columns in the periodic table are called groups or families. Elements in the same group have similar chemical properties. Groups are numbered 1-18. Label the groups 1-18 on your blank periodic table.

Regions of the Periodic Table Metals: As you move further to the left and down, there is more metallic character -Conductors of heat and electricity -Malleable (can be hammered into sheets) -Ductile (can be pulled into wires) -Lustrous (shiny) Nonmetals: -As you move to the right and up, there is more non-metallic character -low boiling point -brittle -dull -good insulator Metalloids -Have properties of metals and non-metals -tend to be good semiconductors in transistors

Groups with Special Names Group 17 (7A): Halogens: -Extremely reactive nonmetals Group 1 (1A): Alkali Metals -soft metals that are extremely reactive Group 18(8A): Noble Gases - Inert gases (un-reactive with other elements) Group 2 (2A): Alkali Earth Metals -shiny reactive metals