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Monday November 1 , 2010. (Periodicity in Atomic Radius). Bell Ringer Monday, 11-1-10. What is meant by the term “periodicity?”. In general terms, periodicity is defined as the quality of recurring at regular intervals . Chemistry defines periodicity as similarities in chemical properties
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MondayNovember 1, 2010 • (Periodicity in Atomic Radius)
Bell RingerMonday, 11-1-10 What is meant by the term “periodicity?” In general terms, periodicityis defined as the quality of recurring at regular intervals . Chemistry defines periodicity as similarities in chemical properties recurring at regular intervals . This leads to the Periodic Law, which states that the physical and chemical properties of the elements are periodic functions of their atomic numbers.
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Periodicity Remember from today’s Bell Ringer that chemistry defines periodicity as similarities in chemical properties recurring at regular intervals . The Periodic Law states that the physical and chemical properties of the elements are periodic functions of their atomic numbers. If you arrange the elements in order of their atomic numbers (number of protons), similar properties will appear at regula intervals. Recall the interval sequence: 8,8, 18, 18, 32
Five Properties of Elements that Display Periodicity Atomic Radius Ionization Energy Electron Affinity Ionic Radius Electronegativity
Atomic Radius Atomic radius may be defined as one-half the distance between the nuclei of identical atoms that are bonded together. A picometer (pm) is a metric unit of length equal to one trillionth of a meter. On your metric staircase, this would be 9 steps below milli- 1x10-12 meter
Atomic Radius Atomic radii decrease from left to right across a period because of the increasing positive charge of the nuclei (more and more p+) pulling the e- closer and closer. Generally speaking, the size of the atoms get smaller as you move from left to right across a period. smaller
Atomic Radius Atomic radii increase from top to bottom down a group because of e- occupying sublevels in successively higher main energy levels. Generally speaking, the size of the atoms get larger as you move from top to bottom down a group. larger
Even thought the lines in each period are not identical, they show a similarity that creates a pattern. This is NOT randomness!
Worksheet The Periodic Law