California Distinguished School P i e d m o n t H i l l s H i g h S c h o o l 1377 Piedmont Road • San José, California 95132-2497 Telephone: (408) 347-3800 • Fax: (408) 347-3805 Periodic Properties of the Elements SY 2018 - 2019 MR. L. MACASAET ROOM D13
Class Activity Write the electron configuration of the elements assigned to you.
Electron configuration and the periodic table
Electron Configuration and the Periodic Table
Electron Configuration and the periodic table
The Periodic Table Dmitri Mendeleev and Lothar Meyer independently came to the same conclusion about how elements should be grouped.
The Periodic Table Chemists mostly credit Mendeleev because he also used chemical properties to organize the table and predicted some missing elements and their expected properties, including germanium.
The Periodic Table Mendeleev’s table was based on atomic masses. It was the most fundamental property of elements known at the time. About 35 years later, the nuclear atom was discovered by Ernest Rutherford. Henry Moseley developed the concept of atomic number experimentally. The number of protons was considered the basis for the periodic property of elements.
Periodicity Periodicity is the repetitive pattern of a property for elements based on atomic number. These are often observed among elements found in a particular location. Trends are oftentimes observed going across a period or down a group for each of them. The following properties are discussed in this chapter: Sizes of atoms and ions, ionization energy and electronegativity.
Effective Nuclear Charge Many properties depend on attractions between valence electrons and the nucleus. Electrons are both attracted to the nucleus and repelled by other electrons. The forces an electron experiences depend on both factors.
Effective Nuclear Charge The effective nuclear charge, Z eff , is found this way:Z eff = Z − S where Z is the atomic number and S is a screening constant, usually close to the number of inner electrons. Effective nuclear charge is a periodic property since it increases across a period.
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