Lewis Dot Diagrams Mr. Buchanan

Energy in the atom Charged particles called electrons surround the nucleus in regions called shells or energy levels Atoms of different elements have different numbers of electrons Each shell is “full” before electrons move to the next shell. Elements of the same group have similar properties because they have the same number of electrons in their outer shell. Electrons that occupy the outer shells are called valence electrons

Noble gas configuration Group 18, the noble gases are the most stable of elements Their valence shell is full with electrons Less energy required Stable Octet

Drawing Lewis Structures http://www.youtube.com/watch?v=eNI9ncjl5HA

Lewis Dot diagrams Visual representation of an element and only its valence electrons Examples: Sodium, Na has one valence so it has 1 dot representing that electron. Chlorine has 7 electrons, 7 dot representing those electrons. Electrons get paired up along 4 sides of the element.

Valence electrons for Elements The valence electrons for the elements can be determined based on the elements position on the periodic table. Lewis Dot Symbol

Writing Electron Dot diagrams The electron configuration for chlorine could be written as: 1s22s22p63s23p5. The core electrons would be 1s22s22p6 while the valence electrons would be in the third shell (or where n = 3). Therefore, chlorine has 7 valence electrons. The Lewis electron dot diagram would look like the following: Notice that the electrons are in groups of two. Think of the chlorine in a box and the box has 4 sides. Each side can have 2 electrons on it. Therefore there can be a maximum of 2 × 4 = 8 electrons on each side.

Writing Electron Dot diagrams Nitrogen has 5 valence electrons. First we write the symbol. Then add the electrons. The s e- go on the top, the px e- go on the right, py on the bottom, and pz on the left. N

Write the electron dot diagram for Na Mg C O F Ne He

Electron Configurations for Cations Metals lose electrons to attain noble gas configuration. They make positive ions. If we look at electron configuration it makes sense. Na 1s22s22p63s1 - 1 valence electron Na+ 1s22s22p6 -noble gas configuration

Electron Dots For Cations Metals will have few valence electrons Ca

Electron Dots For Cations Metals will have few valence electrons These will come off Ca

Electron Dots For Cations Metals will have few valence electrons These will come off Forming positive ions Ca+2

Electron Configurations for Anions Nonmetals gain electrons to attain noble gas configuration. They make negative ions. If we look at electron configuration it makes sense. S 1s22s22p63s23p4 - 6 valence electrons S-2 1s22s22p63s23p6 -noble gas configuration.

Electron Dots For Anions Nonmetals will have many valence electrons. They will gain electrons to fill outer shell. P P-3

Stable Electron Configurations All atoms react to achieve noble gas configuration. Noble gases have 2 s and 6 p electrons. 8 valence electrons . Also called the octet rule. Ar