1. Ch. 12 Notes---Covalent Bonds Covalent Bonds ____________ electrons between two atoms in order to fill the outer energy level (or shell) Each bond involves the sharing of _____ _________ of electrons. Single Bonds= __ e - ’s Double Bonds= __ e - ’s Triple Bonds=__ e - ’s Sharing one pair 246 Sharing is Caring!! Caring is Covalent!!! Sharing

2. Polar and Nonpolar Bonds Even though the electrons in a covalent bond are shared, sometimes the attraction for the bonded pair, (the _____________________), is uneven. This gives rise to 3 bond types. nonpolar covalent bonds: ____________ sharing of the e - pair polar covalent bonds: ________________ sharing of the e - pair ionic bonds: a ___________ of e - ’s from the metal to the nonmetal How To Determine the Bond Type Bond type is based on the electronegativity _____________ between the two bonded atoms. electronegativity equal unequal transfer difference

4. Figure 12.4 The three possible types of bonds. nonpolar polar ionic

5. Figure 12.4: Electronegativity values for selected elements.

6. How To Determine the Bond Type 0 to 0.4 = ______________ covalent bond 0.5 to 2.0 = _____________ covalent bond Above 2.0 = _______________ bond Practice Problems: Determine the type of bond that forms between the atoms in the following compounds. a) CO 2 b) NaClc) CH 4 nonpolar polar ionic 2.5 3.50.9 3.0 2.5 2.1 1.0 = polar covalent2.1 = ionic0.4 = nonpolar covalent

7. Ways to Represent Covalent Bonds in Compounds (1)Quantum Mechanical or Bohr Model of the Atom.

8. Ways to Represent Covalent Bonds in Compounds (1)Quantum Mechanical or Bohr Model of the Atom.

9. Ways to Represent Covalent Bonds in Compounds (3) “Dots” for bonds. (Lewis Structures) a) H 2 H · + · H  b) F 2 :F · + · F:  c) N 2 : N · + · N :  (triple bond) d) NH 3.. · · · · H H:HH:H :F:F: ·· :N::N: H:N:HH:N:H

10. Ways to Represent Covalent Bonds in Compounds (4) “Lines” for bonds. a) H 2 b) F 2 c) N 2 d) NH 3 e) H 2 O.. ¨ ׀ H ׀ H H–H :F–F: :N≡N: H–N–H H–O:

11. ↓ ↑ ↑ Coordinate Covalent Bonds Both of the electrons that make the bond come from the ________ _______________. – Example: CO (carbon monoxide) same element C …___ ___ ___ ___ 2s 2p ↑ O …___ ___ ___ ___ 2s 2p ↓↑ ↑ ↑↓↑ :C O:.. Two of the bonds are “normal”, and the third bond is a coordinate covalent bond. :C O: ← – –

12. The 7 Diatomic Elements Some elements will covalently bond to themselves to form a molecule composed of ____ atoms. These elements are never found in nature as single atoms. Instead, they will be bonded as a ________ when they are in the “_________________” state. The 7 diatomic elements are the gases H, O, N, and all of the _________________, (Group 7A). H 2, O 2, N 2, Cl 2, Br 2, I 2, F 2 “HONClBrIF” two elemental pair halogens

14. Air contains N 2 and O 2 molecules.

15. The decomposition of two water molecules

16. Octet Rule Atoms want ___ e - ’s in their outer shell when forming compounds. This will mean ___ dots around them all together. This is the stable e - configuration of a __________ _______! Important exception: Hydrogen = only needs __ to be full (like He). Other Exceptions: PCl 5 (___ e - ) SF 6 (___ e - ) BF 3 (___e - ) 8 8 noble gas 2 10126

17. Resonance Resonance is the ability to draw 2 or more different e - dot notations that obey the octet rule. Examples: O 3 (ozone) and SO 2 Practice Problem: Draw the resonance structures for CO 3 -2.

18. Properties of Ionic Compounds and Covalent Molecules Molecular: ________________ of electricity formed between two _______________ usually have ________ melting points solubility in water _______: (polar =dissolve; nonpolar = insoluble) forms ______________________solids. For a compound to to conduct electricity it must have: (1) Charged Particles (________) (2) Particles Free to Move (___________ or __________ phase) Insulators nonmetals low varies ions liquidaqueous covalent crystalline

19. Quartz Quartz is the common mineral form of silicon dioxide (SiO 2 ). It is the dominant mineral in most sands and sandstones.

21. Molecular Compounds (“____________”): – Name or formula starts with a ____________ (exception: NH 4 + ) – Other quick ways to tell if the compound is molecular: Name has prefixes and also ends in “-ide”. (It must have both!) Examples: _________________,_______________________ molecules nonmetal carbon dioxidedinitrogen pentoxide

22. Naming Molecular Compounds You do not use the ion sheet for molecules because no __________ are needed. They ______________ electrons instead of transferring them. Use ________________ to indicate the # and kind of atom in the compound. mono=1 di=2 tri=3 tetra=4 penta=5 hexa=6 hepta=7 octa=8 non=9 deca=10 Use the general format shown below… prefix-(except mono)-name the 1st element prefix-name the 2nd element ending with - ide Practice Problems: Name the following molecules. N 2 O 5 CO Cl 4 F 7 SO 3 chargesshare prefixes dinitrogen pentoxide carbon monoxide tetrachlorine heptafluoride sulfur trioxide

23. Writing Molecular Formulas The prefixes in the name tell you the # of atoms of each element there are. (Those become the _________________ in the formula!) Practice Problems: Write the formula for each molecule. nitrogen monoxide carbon tetrachloride diphosphorous pentoxide subscripts NO CCl 4 P2O5P2O5