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Periodic Table Shortcut Noble Gas Notation Lewis Dot Structures. When we write electron configurations, do we need to always start at the beginning?. No, there are a few shortcuts. The first shortcut involves the placements of element’s on the periodic table.
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Periodic Table ShortcutNoble Gas NotationLewis Dot Structures
When we write electron configurations, do we need to always start at the beginning? No, there are a few shortcuts.
The first shortcut involves the placements of element’s on the periodic table • Let us look at the electron configurations from yesterday’s homework and bell work from today and see how they fall on the periodic table. • You will need 4 color pencils for this to color the areas of the s, p, d, and f orbitals.
So, the periodic table is arranged with electron configurations in mind The only exception is He
The rows and columns • The rows correspond to the principle quantum number (n) • In other words, each time you drop a row on the periodic table, you go out an energy level. • Be careful with the d and f areas • The d area is n-1 and the f area is n-2 • La and Ac are considered the first f area elements • The sets of columns correspond to l quantum numbers and the amount of electrons in that orbital
So, by looking at the periodic table, one can find an element’s electron configuration
Let’s try some examples:Remember it should be a number then a letter then a superscript • What is the last orbital of tin (Sn)? • What is the last orbital of Ruthenium (Ru)? • What is the last orbital of Holmium (Ho)? • What element ends with the electron configuration of: • 5s1 • 6p4 • 5f3 (remember Ac is first f)
The second shortcut • We need to find a group of elements that have completed or full orbitals. • That group is the noble gases. • The last column on the periodic table. • This group can be used to write an abbreviated version of an element’s electron configuration.
How to write Noble Gas Notation • Find the closest noble gas to the element in atomic number without going over. • Write that noble gas’s symbol in brackets. • Go back to the beginning of the row and work back to the elements writing down the orbital sections and counting the electrons as you go.
Examples • As (Atomic Number – 33) • What is the closest Noble gas without going over? • Ar • So, [Ar] • C • [He]2s22p2 • Pb • [Xe] 4s2 3d10 4p3 6s2 4f14 5d10 6p2
Lewis Dot Formulas • Shows the valence electrons of an atom • Valence electrons are the electrons in the outermost energy level • The only electrons that are in the outermost energy level are s and p. • Therefore, the most valence electrons an atom can have is 8 (2 from the s and 6 from the p).
Lewis Dot Formulas • So, Lewis Dot Formulas are the chemical symbol surrounded by dots. • There will be one dot per electron in the s and p orbital • Hund’s rule must be followed
What is the Lewis Dot Structure for the following? • Francium • Arsenic • Hydrogen • Krypton • Oxygen