Bonding with Chemistry Lewis Dot Structures VSEPR and Molecular Geometry

A chemical bond is made by sharing electrons between two atoms to achieve the outer electron configuration of the noble gases. Chemical Bonds IonicCovalent Polar (dipole moment) Nonpolar

Each element has a preferred outer shell electron configuration. An element tends to form enough bonds to achieve the number of electrons corresponding to the nearest noble gas. This is a periodic (repeating) property of each column (family) of elements.

So the number of outer shell electrons can be determined from the periodic table: 1H1H 2 He 3 Li 4 Be 5B5B 6C6C 7N7N 8O8O 9F9F 10 Ne 11 Na 12 Mg 13 Al 14 Si 15 P 16 S 17 Cl 18 Ar 19 K 20 Ca 21 Sc 22 Ti 23 V 24 Cr 25 Mn 26 Fe 27 Co 28 Ni 29 Cu 30 Zn 31 Ga 32 Ge 33 As 34 Se 35 Br 36 Kr 37 Rb 38 Sr 39 Y 40 Zr 41 Nb 42 Mo 43 Tc 44 Ru 45 Rh 46 Pd 47 Ag 48 Cd 49 In 50 Sn 51 Sb 52 Te 53 I 54 Xe 55 Cs 56 Ba 57 La* * 72 Hf 73 Ta 74 W 75 Re 76 Os 77 Ir 78 Pt 79 Au 80 Hg 81 Tl 82 Pb 83 Bi 84 Po 85 At 86 Rn 87 Fr 88 Ra 89 Ac* * 104 Rf 10 5 Ha 106 Sg 107 Ns 108 Hs 109 Mt Etc.

Lewis dot structures provide a simple means to determine bonding capacity: Bonding requirements for achieving an octet of electrons in the outer orbital: ElementBonds needed C4 N3 P3 or 5 O2 S2 or 6 F1 Cl1 Br1 I1 H1

VSEPR = valence shell electron pair repulsion theory indicates what molecular geometry we expect.

Essential bonding characteristic of carbon atoms: Carbon has 4 outer shell electrons. It needs 4 more to achieve the Neon configuration of 1s 2 2s 2 2p 6. It forms 4 bonds total. Never forget this. It will help you a lot!!!

Review: How many bonds does hydrogen form? How many bonds does oxygen form? How many bonds does carbon form? What is the molecular geometry of water? What is the molecular geometry of oxygen gas? What is the molecular geometry of CH 4 ?

Organic chemistry

We begin with Hydrocarbons Hydrocarbons are composed of the elements __________ and __________, just like the name implies. Three major classes of hydrocarbons Alkanes Alkenes Alkynes

Speaking of alkanes, alkenes, alkynes, etc: Every subject has its own language. Listen to military people talk and you know this is true! Organic chemistry is positively loaded with new language to learn. Hang in there, it will come with time…

Alkanes aka saturated hydrocarbons Structure Names = nomenclature Properties Physical Chemical

We don’t have to stop at C10… for example, C20 is called eicosane. We’ll see that in a later chapter. # CarbonsName 1methane 2ethane 3propane 4butane 5pentane 6hexane 7heptane 8octane 9nonane 10decane Counting the organic way

Melting and boiling points of alkanes

Cycloalkanes Structural features Nomenclature Properties: similar to noncyclic alkanes

Alkenes aka unsaturated hydrocarbons Structural features Nomenclature Properties Physical Chemical

Melting and boiling points of alkenes

Alkynes aka unsaturated hydrocarbons Structural features Nomenclature Properties Physical Chemical

More families of organic compounds: When we introduce other atoms than carbon and hydrogen into hydrocarbons, we call these functional groups. They have their own special names.

Examples of functional groups:

More examples of functional groups in molecules:

Review: Chemical bonding re: carbon compounds How many bonds? Three major classes of hydrocarbons Counting the organic way: Recognizing functional groups

Problems to practice on: Chapter 11 & Chapter 12: check out the chapter problems sheet for recommended problems for practice.