Name the following compounds: Monday, November 17, 2014 Objective: Students will be able to draw electron dot diagrams for covalent molecules. Warm-Up: Name the following compounds: S4N2 Na2O Cr(MnO4)3 Agenda: Electron Dot Diagram Notes and Practice

Electron Dot Diagrams

Review Electron Dot Diagrams are a short hand way to show the valence electrons in an atom. Valence electrons: are the number of electrons in the outermost energy level of the atom.

Review A covalent bond is between two or more non-metals. When atoms don’t have 8 valence electrons, they can share electrons between them in order to get 8. We can also draw Electron Dot diagrams to show how the electrons are shared in a molecule.

Types of Covalent Bonds Single Bond: two atoms sharing 2 electrons Double Bond: two atoms sharing 4 electrons Triple Bond: two atoms sharing 6 electrons

Brain Break: Count-Up

Steps to Draw Electron Dot Diagrams: Determine the arrangement of atoms and draw a skeleton structure. The central atom is usually the one with the lowest electronegativity or the single atom. The central atom is NEVER hydrogen! Draw the Electron Dot Diagram for each atom. Remember: you can find the valence electrons by the Group the element is located in.

Steps (cont.): Connect the atoms with a single line. This line denotes the 2 electrons being shared. Check to see if all atoms have the desired amount of valence electrons. Remember: Hydrogen and Helium only want two electrons to be happy and Boron is unique because it only wants 6 electrons to be happy. All other elements want 8.

Examples: CH4 H2O2 BF3

What happens if there aren’t enough lone pairs for all to have 8? Add an “extra” bond for every 2 electrons you’re short! CO2 N2