Bell Ringer You will need your Periodic Table
Bell Ringer ► You will need your Periodic Table… ► Construct a Bohr diagram and a Lewis dot Structure for Potassium, Fluorine, and Arsenic
The History and Arrangement of the Periodic Table
History of the Periodic Table ► 1869 – Dmitri Mendeleev (Russian Chemist) thought elements may have something in common. ► Organized the elements into a table ► Made each element a card and listed its properties known at the time (mass, density, color, melting point and valence number).
Dmitri Mendeleev (cont. ) ► Mendeleev organized each card (element) according to its atomic mass (mass #) ► Noticed a repeating pattern of valence numbers (1, 2, 3, 4, 5 etc. . ) ► Noticed elements fell in to columns (groups) ► Noticed all elements in a column had the same valence number and showed similar physical and chemical properties.
Henry Moseley ► Mendeleev left blank spaces in his table so elements would line up – he also predicted what properties the undiscovered elements would have. ► 1913 – Henry Moseley (English Scientist) changed the arrangement of the periodic table. Instead of by increasing atomic mass (mass #), it was arranged by increasing: atomic number (# of protons).
Arrangement of the Periodic Table ► Systematic arrangement of the elements ► Arranged by atomic number and properties ► Numbered groups / families are in vertical columns ► Periods are by amount of energy levels in horizontal rows (1 -7) ► Divided into metals, nonmetals and metalloids
Metals - properties ► Elements that begin at the left side of the periodic table ► Good conductors of electricity ► Shiny ► Ductile – can be drawn into thin wires ► Malleable – can be hammered into thin sheets and other shapes ► High melting point ► Tend to loose electrons
Nonmetals - properties ► Elements that are to the right of the zigzag on the periodic table ► Not shiny, dull in appearance ► Do not conduct heat or electricity ► Are brittle and break easily ► Cannot be drawn into wire or hammered into sheets ► Lower densities ► Lower melting points ► Tend to gain electrons
Metalloids - properties ► Elements that are found along both sides of the zigzag line ► Solids ► Can be shiny or dull conduct heat and electricity better than nonmetals but not as well as metals ► Both ductile and malleable
Chemical Groups (Families) ► Elements that are in the same group or family (column) of the Periodic Table have similar properties because they have the same number of valence electrons
Group (Family) 1 - Alkali Metals ► 1 valence electron in outer energy level ► Very reactive substances so it easily bonds with other substances ► Easily loses 1 electron to form a stable +1 ion (ionic bond) ► Never found alone in nature ► Soft, silver-white, shiny
Group (Family) 2 - Alkaline Earth Metals ► 2 valence electrons in outer energy level ► Loses 2 electrons to form +2 ions ► Second most reactive elements but not as reactive as group #1, so bonds easily with other substances ► Never found alone in nature ► Will always bond ionically in nature ► Found combined with oxygen and other nonmetals in the Earth’ crust
Groups 3 -12 ► 1 The Transition Metals or 2 valence electrons ► Can lose and or share valence electrons ► Can have many multiple electrons in 2 nd to last energy levels ► Common metals – gold, silver & copper ► The U. S. imports at least 60 of these types of elements which are strategic and vital for our economy
From Metals to Nonmetals (outer energy level) ► Group 13 – Boron Group/Family 3 valence electrons - metalloids and metals in group - usually bonds covalently ► Group 14 Carbon Group 4 valence electrons - non-metals, metals and metalloids - will always bond covalently ( electron sharing) - contain elements which are essential for cell functions
► Group 15 Nitrogen Group 5 valence electrons - non-metals, metalloids and metals - will always bond covalently ► Group 16 Oxygen Group 6 valence electrons - non-metals, metalloids and metals - will bond covalently and ionically in nature ► Group 17 Halogen Group 7 valence electrons - all non-metals that are very reactive and form compounds called halides ( salts) - bonds covalently and ionically
► Group 18 Noble Gases 8 valence electrons - colorless - non-reactive ( inert ) / very stable - have a full outer shell filled with electrons - non-metals
Rare Earth Elements (Inner Transition Metals) ► First Row – Lanthanide Series - naturally found rare Earth metals - all but one is non-radioactive ► Second Row – Actinide Series - most are man-made and radioactive - many are short-lived
- Slides: 17
