1. Electron Arrangements Lewis Dot Structures

2. Learning Objectives Express the arrangement of electrons in atoms using Lewis valence electron dot structures Electron Arrangements

3. Valence electron – an electron in an atom’s highest occupied energy level – Outermost electrons of the electron cloud – Establish chemical characteristics of elements – Only electrons shown in Lewis electron dot structures Symbolized as dots Lewis Dot Structures

4. Number of valence electrons is the same as the group number for representative elements Lewis Dot Structures

5. Helium is an exception because its highest occupied energy level can only hold two electrons Lewis Dot Structures

6. Number of valence electrons determines behavior – Elements in the same group have similar chemical properties Lewis Dot Structures

7. Drawing an Electron Dot Structure Step 1 Step 2 Identify the symbol for the element and its number of valence electrons using the periodic table. Place the corresponding number of electron dots around the symbol. Imagine that the symbol has four sides: top, right, bottom, and left. Begin by assigning one dot per side, moving clockwise around the symbol. Then, if there are still more dots to assign, start adding a second dot to each side until all of the valence electrons have been accounted for.

8. Drawing an Electron Dot Structure Ex) Draw the electron dot structure for phosphorus. Identify the symbol for the element and its number of valence electrons using the periodic table. Place the corresponding number of electron dots around the symbol. Imagine that the symbol has four sides: top, right, bottom, and left. Begin by assigning one dot per side, moving clockwise around the symbol. Then, if there are still more dots to assign, start adding a second dot to each side until all of the valence electrons have been accounted for. Step 1 Step 2 Does the result make sense? The symbol for phosphorus is P. Phosphorus is in group 5A so it has 5 valence electrons. Yes.

9. Learning Objectives Express the arrangement of electrons in atoms using Lewis valence electron dot structures Electron Arrangements