Weekly Blog 12/15

This week in chemistry we learned about ionic and covalent bonds, double bonds, triple bonds, the properties of ionic and covalent elements and the Lewis Dot Structure.

Ionic

• Brittle & Hard
• Good Conductor
• High Boiling Point
• Metal/Nonmetal
• Soluble in Water
• Transfer of Electrons

Covalent

• Soft
• Poor Conductor
• Low Boiling Point
• Nonmetal/Nonmetal
• Not Soluble in Water
• Sharing of Electrons

For the Lewis Dot Structure for covalent bonds, the bond must meet the octet rule, besides the exceptions of hydrogen and helium (2 electrons), and Boron (6 electrons).

Steps for drawing the Lewis Structure:

1. Draw the element symbols connected by a line. C is always in the middle. H is always on the outside. Single elements are surrounded by others. 
2. Count all of the valance electrons for the compound. The valance electrons for each element are the same as its group number.
3. Since each line represents a bond (2 shared electrons), subtract 2 from the total number of valance electrons for each line drawn.
4. The remaining electrons are placed in pairs around the compound working from the outside in.
5. Check for stability. Elements need to have 8 electrons around themselves. Hydrogen needs 2. Boron needs 6. Remember that a line represents two electrons.
6. If atoms are not stable (need more electrons), erase a pair of electrons from a neighbor atom and draw another bond between them. There will never be more than 3 lines (bonds) between elements.