1. Note guide 5-1Basic Bonding Review --Elements combine to form a new substance. Why? Unstable elements (atoms) want to be stable, so they bond with other unstable elements (atoms) = Octet Rule (outer energy level has 8 electrons, meaning the atom is stable and reached noble gas config) --Electrons are the sub-atomic particle which is responsible for bondingbonding. Is it all of the electrons? NO! The valence electrons (found in the last primary energy level) are the ones that bond. --So how do these valence electrons bondbond? Well it depends on what the electrons do.

2. How they Bond 1. IonicallyIonically --Electrons transferred from one atom to another. Cations (+ charged atoms) and Anions (- charged atoms) formed when atoms gain or lose valence electrons. Well who gains, and who loses? Please tell us ol’ wise one! -- Metals have a low number of valence electrons so it is easier for them to lose their valence electrons to get to a complete octet than to gain to stability. Therefore, they are cations. --remember, when naming the cation we just use the element name. --Transition metals (the B’s) are a bit strange. The charge of the cations may vary. Iron (Fe) for example can lose 2 or 3 valence electrons. Remember, we show those that have multiple ions with its charge in roman numbers = Iron (II)

3. --when naming anions remember we drop part of the element name and add suffix –ide. --Nonmetals have a high number of valence electrons so it is easier for them to gain electrons to get to a complete octet. There fore they are anions. --Ionic compounds are electrically neutral even though they are composed of ions. The charges of all ions in the compound balance out. --Most ionic compounds are crystalline solids at room temp and generally have high melting points. 2. Metallic --the valence electrons of metal atoms can be molded as a sea of electrons. --the bonds are free floating valence electrons for the + charged metal ions, therefore a bond between valence elctrons and cations. --this sea of electrons give metals their properties….malleability and ductile, etc.

4. Bonding between atoms takes place because atoms crave stability. 1.True 2.False

5. All electrons within an atom are involved in the bonding process. 1.True 2.False

6. According to the octet rule, an atom needs to achieve _____ electrons in its highest energy level to become stable. 1.8 2.18 3.32 4.None of above

7. How many valence electrons does an atom of any element in group 6A have? 1.2 2.4 3.6 4.8

8. When an aluminum atom loses its valence electrons, what is the charge on the resulting ion? 1.2+ 2.2- 3.3+ 4.1+

9. An ionic compound is 1.Electrically neutral 2.Held together by ionic bonds 3.Composed of anions and cations 4.All of the above

10. 5-2 Covalent bondingCovalent bonding --Like ionic bonds, covalent bonds follow the octet rule when bonding. --covalent bonds involve the sharing of electrons to achieve stability, or to achieve the noble gas electron configuration – a full outer energy level (8 e - )noble gas electron configuration Single covalent bondscovalent bonds --this involves two atoms sharing one pair of electrons Ex: Hydrogen gas H + H  H:H yellow are shared pair e - H atom H atom produces Hydrogen molecule --the dots represent outer energy level electrons --after using the dots, we replace with dashes to represent the bond (draw fluorine bonding on page 218 into notes)

11. --in the above diagram of a fluorine molecule notice that each F contributes only one electron to the sharing process, leaving other pairs of electrons not sharing = unshared pair --can draw for diatomic molecules (H 2 ) or molecules of compounds (H 2 O) Draw H 2 O into notes pg 218 --when carbon bonds with other atoms, it usually forms four bonds. --Conceptual problem 8.1 pg. 220 (read and understand) --Do practice problems in your note guide from page 220. Include each molecule name

12. 5-2 day 2: Double and Triple Covalent Bonds Atoms can share more than one pair of electrons --Double Covalent Bond – when atoms share 2 pair (4 total valence electrons). Shown by 2 dashes between bonding elements EX: O 2 (draw oxygen bond on page 221) --side note: through experimentation, oxygen is one of the exceptions which do not follow the octet rule. --cannont draw an accurate electron dot diagram --Triple Covalent Bond – bond formed when sharing 3 pairs of valence electrons (6 total electrons). Shown by 3 dashes Ex: N 2 (draw nitrogen bond on page 221)

13. Coordinate Covalent Bond (shown by an arrow  instead of dash – ) --bond in which one atom contributes both bonding electrons Ex: Carbon Monoxide (draw carbon monoxide picture – pg. 223) Polyatomic ion Polyatomic ion = tightly bound group of atoms that has a positive or negative charge AND behaves as a unit (NH 4 + ) --most polyatomic ions and cations have both covalent and coordinate covalent bonds. This means that these compounds include both ionic and covalent bonding Copy table 8.2 (pg. 224)for the following: hydrogen peroxide, sulfur dioxide, nitric oxide, Hydrogen chloride

14. Conceptual problem 8.2 pg. 225 --read and discuss Practice problems 9, 10, 11 (SO 4 2- )

15. Note Guide 5-2 day 3 Energy is required to break bonds. For example, it would take 435 kJ to break apart all of the bonds in 2 grams of H 2 --this energy that is required to break covalent bonds is called bond dissociation energy. --a larger the bond dissociation energy, the larger the bond. More energy is required to break it! EX: Carbon to carbon bonds are strong, therefore it takes a lot of energy to break the bonds. Because it takes so much, compounds with only Carbon and Carbon - Hydrogen single covalent bonds are usually unreactive. (methane) Resonance --sometimes it is possible to draw 2 or more valid electron dot structures having the same number of electron pairs for a molecule or ion.

16. --these are called resonance structures -we show resonance structures using  double headed arrows. EX: Ozone bonding (draw formula on pg 227 in notes) -back in the day, it was thought (incorrectly) the electron pairs would flip back and forth amongst the electron dot structures. Octet Rule exceptions --cannot use the octet rule in molecules whose total number of valence electrons is an odd number. --also, there are times when atoms within molecules have less or more than a complete octet. EX: Nitrogen Dioxide (NO 2 ) has 17 total valence e - s --so when it bonds, there is an unpaired electron present (see drawing pg. 228)

17. --there are also times when an even numbered molecule fails to meet the octet rule: --EX: some boron compounds (see bottom of pg.228) --and there are times the octet rule is expanded to include more electrons. Phosphorus and sulfur sometimes do this

18. 5-3 Note guide --Polarity: - when atoms bond covalently, the sharing electrons are pulled between the nuclei of the atoms sharing the electrons --if this tug of war happens and they get pulled equally, we call the bond nonpolar covalent. --this occurs when atoms of the same element bond EX: H 2 ; O 2 ; N 2 --if this tug of war happens and the sharing electrons get pulled closer to one nuclei than the other, we call the bond polar covalent. --electronegativity values of each atom will determine which atom pulls and which atom gets pulled.

19. -- The more electronegative atom attracts electrons more strongly and gains a slight negative charge. --the less electronegative atoms then ends up with a slightly positive charge Electronegativity difference range Probable bond typeExample 0.0 – 0.4Nonpolar covalent H-H (0.0) 0.4 – 1.0Moderately polar H-Cl (0.9) 1.0 – 2.0Very polar H-F (1.9 ) > or equal to 2.0Ionic Na + Cl - (2.1)

20. Attractions between molecules --molecules can attract each other by a few forces. These forces are weaker than ionic or covalent bonds, but they are important. 1. VanderWaals forces – weakest attractions --dipole interactions – polar molecules are attracted to each other --dispersion forces – caused by motion of the electrons 2. Hydrogen bonds – attractive forces in which a hydrogen covalently bonded to a very electronegative atom is also weakly bonded to an unshared electron pair of another electronegative atom (can be in same molecule or a neighbor molecule. --keep in mind a covalent bond must exist between a hydrogen atom and a highly electronegative atom for a hydrogen bond to form.