Unit Seven: Periodic Table

Background to the Periodic Table: Elements are arranged on the periodic table according to similar properties. The modern periodic table is organized by increasing atomic number.

Background to the Periodic Table: Ted ed: Periodic Table Dimitri Mendeleev , a Russian scientist, is credits for creating the first periodic table in 1869. At that time, there were only 60 known element and Mendeleev organized them according to their atomic mass. Mendeleev was able to predict the properties of missing elements which were later discovered. These elements fit perfectly in the missing gaps. Henry Mosely later rearranged the periodic table based on increasing atomic number. This arrangement is still used today. The columns on the periodic table are called groups, the rows are called periods. There are 18 groups (columns) and 7 periods (rows) on the periodic table.

Period Group or Family Group or family Period

Classification of Elements Elements on the periodic table can be classified in one of the three following groups: Metals Nonmetals Metalloids Metals are located on the left side of the periodic table Non metals are located on the right side of the periodic table. The six metalloids fall along the “steps”. They include: Boron (B), Silicon (Si), Germanium (Ge), Arsenic (As), Antimony (Sb), Tellurium (Te)

Classification of the Periodic Table:

Properties of Metals Metals are good conductors of heat and electricity Metals are malleable Metals are ductile Metals have high tensile strength Metals have luster

Examples of Metals Potassium, K reacts with water and must be stored in kerosene Copper, Cu, is a relatively soft metal, and a very good electrical conductor. Zinc, Zn, is more stable than potassium Mercury, Hg, is the only metal that exists as a liquid at room temperature

Properties of Nonmetals Carbon, the graphite in “pencil lead” is a great example of a nonmetallic element. Nonmetals are poor conductors of heat and electricity Nonmetals tend to be brittle Many nonmetals are gases at room temperature

Examples of Nonmetals Microspheres of phosphorus, P, a reactive nonmetal Sulfur, S, was once known as “brimstone” Graphite is not the only pure form of carbon, C. Diamond is also carbon; the color comes from impurities caught within the crystal structure

Properties of Metalloids Metalloids straddle the border between metals and nonmetals on the periodic table. They have properties of both metals and nonmetals. Metalloids are more brittle than metals, less brittle than most nonmetallic solids Metalloids are semiconductors of electricity Some metalloids possess metallic luster

Silicon, Si – A Metalloid Silicon has metallic luster Silicon is brittle like a nonmetal Silicon is a semiconductor of electricity Other metalloids include: Boron, B Germanium, Ge Arsenic, As Antimony, Sb Tellurium, Te

Periodic Table: Metallic arrangement Layout of the Periodic Table: Metals vs. nonmetals Nonmetals Metals

Reading the Periodic Table: Classification Nonmetals, Metals, Metalloids, Noble gases

Groups/Families and Chemical Properties: The vertical columns on the periodic table are called groups. There are 18 groups on the periodic table. Elements in a group have the same valence electrons and because of this, they have similar chemical properties.

Down the Periodic Table Family: Are arranged vertically down the periodic table (columns or group, 1- 18 ) These elements have the same number electrons in the outer most shells, the valence shell. Alkali Family: 1 e- in the valence shell Halogen Family: 7 e- in the valence shell

Groups/Families and Chemical Properties: Table of element families & properties: Group #1 Alkali Metals Reactive, soft metals, 1 valence electron Group #2 Alkaline Earth Metals Reactive metals, harder than alkali metals, 2 valence electrons Group #17 Halogens Reactive non-metals 7 valence electrons Group #18 Noble Gas Unreactive non-metals, all are gases 8 valence electrons

Infamous Families of the Periodic Table Notable families of the Periodic Table and some important members: Alkali Alkaline (earth) Transition Metals Noble Gas Halogen Chalcogens