Electron Dot Diagrams

• The nucleus is represented by the atomic symbol
• For individual elements, you have to determine the number of valence electrons, which are represented by the dots around the atomic symbol
• To find the number of valence electrons is simple, look at the group number the element is in and that shows you the number of valence electrons
• There are four orbitals on each side of the nucleus holding a maximum of two electrons
• Each orbital gets 1 electron before they pair up, making a lone pair

 

Here are some examples of electron dot diagrams for sodium, magnesium and chlorine

Lewis diagrams for compounds and ions

• In covalent compounds, electrons are shared

Follow these two easy steps and learn how to draw a Lewis diagram for compounds and ions

1.       Determine the number of valence electrons for each atom in the molecule, which I explained above

2.       Place atoms so that valence electrons are shared to fill each orbital

This example shows the Lewis diagram for NF3

Double and triple bonds

Helpful Hint: Sometimes the only way covalent compounds can fill all their valence levels is if they share more than one electron

Lewis diagrams: Ionic compounds

• In ionic compounds electron transfer from one element to another
• Determine the number of valence electrons on the cation. Move these to the anion
• Draw [ ] around the metal and the non-metal
• Write the charges outside the brackets