Notes #5: Electronegativity WCHS Chemistry

Covalent Bonds Ionic Bonds IONIC & COVALENT BONDS Covalent Bonds e- are shared to reach 8 Ionic Bonds Give or take e- Opposites attract _ + Equal Sharing Unequal Sharing **Sharing isn’t always equal!** Electronegativity = the ability of an atom to attract e- A.k.a. How much an atom can “pull” on an e-

(How hard an atom can pull on e-) Atoms don’t pull as hard Increases (pulls more) Closer & closer to 8 v.e- Atoms pull harder on e- Atoms get bigger: e- far away Decreases (less pull) Atoms don’t pull as hard

F pulls so hard that it takes the e- from K 4.1 4.1 4.1 4.1 0.91 2.5 F pulls so hard that it takes the e- from K Equal pulling, so equal sharing F pulls harder, so e- stays closer to F

NONPOLAR Covalent Bond = NOT CHARGED b/c of EQUAL sharing of e- 4.1 4.1 NONPOLAR Covalent Bond = NOT CHARGED b/c of EQUAL sharing of e- POLAR Covalent Bond = Slightly CHARGED b/c of UNEQUAL sharing of e- Must write in slight charges or “poles” like on a battery! 𝛅- 𝛅+ 2.5 4.1

BIG IDEAS Not all sharing is equal Unequal sharing = POLAR covalent Equal sharing = NONPOLAR covalent NO sharing = IONIC!

*Draw Lewis Dot structures 1st to see which elements are involved in a bond EXAMPLES 0.3 difference 2.2 2.5

Look at chart on bottom of page...

*Draw Lewis Dot structures 1st to see which elements are involved in a bond EXAMPLES 0.3 difference NONPOLAR Covalent (Equal Sharing) 3.07 2.2 2.2 𝛅- 2.5 𝛅+ 0.87 difference POLAR Covalent (Unequal Sharing)

EXAMPLES IONIC NO sharing _ + *Draw Lewis Dot structures 1st to see which elements are involved in a bond EXAMPLES IONIC NO sharing 1.01 2.83 _ + 1.82 difference

No Poles → Equal sharing POLES (slight charges) → Unequal sharing NO SHARING! → Full charges (take or give e-)

Steps for Classifying Bonds: Draw all Lewis Dot Structures IMPORTANT: In the future → Check ALL BONDS! There can be MULTIPLE types of bonds in one molecule! Steps for Classifying Bonds: Draw all Lewis Dot Structures Assign EN numbers and check differences between all UNIQUE bonds Use chart to determine nonpolar, polar, or ionic Assign slight charges if polar or full charges if ionic