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The Periodic Table. SC Standards. PS-2.3 Explain the trends of the periodic table based on the elements’ valence electrons and atomic numbers. PS-2.5 Predict the charge that a representative element will acquire according to the arrangement of electrons in its outer energy level.
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SC Standards PS-2.3 Explain the trends of the periodic table based on the elements’ valence electrons and atomic numbers. PS-2.5 Predict the charge that a representative element will acquire according to the arrangement of electrons in its outer energy level.
Dmitri Mendeleev • A Russian Chemist in the Mid 1800’s • Found information about the 63 elements that were known at that time • Arranged the Periodic table according to atomic mass
Henry Moseley • British scientist of the early 1900’s • Arranged the periodic table based on atomic numbers • Modern Periodic Table
The Periodic Law • The physical and chemical properties of the elements are periodic functions of their atomic numbers
…That means their physical and chemical properties form repeating patterns. (Kind of like the days of the month form repeating weeks on a calendar.)
Metals • Nonmetals • Metalloids How the elements group up, develops a Periodic Table…PATTERN!!
Periods Groups and Electron Dot Notation
Elements in the same period have the same number of energy levels. (This is a PATTERN!!)
Electron Cloud Structure • Electron clouds are arranged by energy levels • Level 1 – closest to the nucleus, least amount of energy • Maximum of 2 electrons • Level 2 – maximum 8 electrons • Level 3 – maximum 18 electrons • Level n – further out, greater the amount of energy
Elements in the same group will have the same number of electrons in their outer energy level. Therefore, they will have similar properties. (This is a PATTERN!!)
Valence Electrons • The electrons that an atom has in its outer most energy level are called its valence electrons. • The maximum number of electrons in the outer most energy level is 8. (Except for level 1, which can only hold 2.)
* * X * * * * * * Electron Dot Notation(also called a Lewis Structure) • A simplified way to show how the electrons are arranged in their outer energy level. • Dots are placed around the element symbol
Here’s a HINT!!! • The Group # helps you figure out the number of dots on your notation!!! Ex: Nitrogen Group 15 gets 5 valence electrons N
Let’s Practice • Draw the dot diagram for • Mg • C • O • Cl • K