Covalent Bonds Chapter 6

Formed when electrons are shared between two nonmetals Covalent Bonds Formed when electrons are shared between two nonmetals

Types of Covalent Bonds There are two types of covalent bonds, polar and nonpolar covalent bonds. Non polar covalent bonds- The electrons are equally distributed among the elements involved.

Types of Covalent Bonds Polar covalent bonds- There is an uneven distribution of electrons around the nuclei of the elements involved

The attraction between the bonds differ due the electronegativity Remember that electronegativity determines the ability of an atom to attract electrons to itself The attraction between the bonds differ due the electronegativity If one of the elements in the covalent bond has a higher electronegativity then it will have a greater pull on the other electrons

Table of Electronegativity All covalent bonds have an electronegativity of less than 1.7

Polar Vs Nonpolar Covalent Bonds Polar covalent bonds have an electronegativity value of less than 1.7, but greater than 0.4. Nonpolar covalent bonds have an electronegativity value of less than 0.4 CO carbonmonoxide (Oxygen 3.44 ), (Carbon 2.55) 3.44- 2.55 = 0.89 (polar covalent bond)

Electrons are not shared equally Polar Covalent Electrons are not shared equally One atom will be more negative than the other Partial charges results in a polar bond called a dipole bond

Nonpolar Covalent Bond Electrons are shared equally No partial charges exist in the molecule

Lewis Structures of Covalent Bonds Essential Questions: List the six basic steps used in writing Lewis structures for covalent bonds.

Six Step to Create Lewis Structures Determine which element is the central element of the structure( the element with the least electronegativity). All other molecules become terminal elements. Find the total amount of valence electrons that the molecule uses for bonding by adding all of the valence electron for each element present in the molecule. Divide the total number of electrons by 2. This gives you the amount of bonding pairs the molecule could have.

Six Steps to Create a Lewis Structure 4. Place one bonding pair between the central element and each terminal element 5. The remaining pairs will be assigned to the terminal elements to complete the octet rule. Leftovers will be assigned to the central element. 6. Count the amount of electron in the structure. Make sure they equal to the amount of electrons available

Practice 1. NH3 2. H2S 3. SiH4 4. PF3 5. IBr 6. CH3Br 7. C2HCl 8. SiCl4 9. OF2 10. BCl3