Carbon and its compounds… Organic Chemistry!! Chapter 25 (in the textbook), Unit X in Hebden (pg 214-244)

Organic Chemistry - What is it and why does it exist? Organic chemistry is the study of carbon containing compounds. They can also contain other elements like… H, O , N, P, and halogens. However, they do not include the compounds CO or CO2 or carbonate (CO3 ) or cyanide ( CN ) compounds. Easy tip – Organic compounds have to contain a… C and an H (and the C must be written first!)

Organic compounds account for about 90% of all chemical compounds as there are several million different carbon compounds known and as many as 30, 000 new ones are synthesized each year! Carbon has 4e- in its outer (valence) shell. It shares these four electrons with other elements that also want to share their electrons. e.g. H, O, P, S, N, and the halogens When this sharing occurs, covalent bonds are formed. e.g. C will share electrons with other C atoms to form straight and branched chains of C atoms.

Why can carbon form so many different compounds? 1) It has 4 possible boding sites (think of the Lewis structure). Few elements have 4 bonding sites!! It could be 4 single bonds, a double bond and 2 singles, a triple bond and a single. There are so many possibilities!

Why can carbon form so many different compounds? 2) It’s size- It is relatively small and holds it’s e-tightly, so therefore when it bonds, it makes short and strong covalent bonds 3) It’s ability to form long chains - Long chains make up the framework for a large variety of compounds (ie DNA, body proteins, carbohydrates,)

How many bonds can carbon make if… ? ? C - ? C = ? ? C = ?

Fast Fact: C will join with 4 hydrogen atoms to form CH4 (methane). C forms a special type of bond called sp3 hybrid orbitals. These are blendings of one s- and three p- orbitals. This tetrahedral (3D)shape allows the e- to stay as far apart from eachother as possible (remember... they repel). The bond angles made between the e- are at 109.5º

Allotropes of Carbon in nature (see p. 806-807) Allotropes of Carbon in nature (see p. 806-807) -forms of the same element that have different bonding patterns Amorphous carbon (charcoal, coal, peat) A mixture of different C-compounds Graphite Two-dimensional bonding of C-atoms in flat planes ( in sheets) Weak C-bonds allow the sheets of C planes to slide by each other and so it is used as a lubricant (what’s in your pencils!!) Diamonds Strong 3-dimensional bonding among all C-atoms in a tetrahedral arrangement Hardest known natural substance Fullerenes or “Bucky balls” Hollow spheres like a soccer ball composed of 60-80C atoms bonded in pentagons and hexagons Possible uses include better lubricants, new superconductors, cages to carry medical molecules into sick tissue

Types of Organic Compounds!! The millions of organic compounds are broken up into groups based upon functional groups A Functional group is defined as any atom/group of atoms that has a characteristic chemical behavior. Functional groups determine the specific properties of a molecule. (how it will react) You must memorize these Functional groups!!

1) Hydrocarbons C6H14 – Molecular formula Condensed Formula OR CH3 – CH2 -- CH2 -- CH2 -- CH2– CH3 1) Hydrocarbons Compounds containing ONLY Carbon and Hydrogen atoms (However, if one or more hydrogen atoms are replaced by another atom or group of atoms, then this is called a substituted hydrocarbon or a saturated hydrocarbon) .

Branches of Hydrocarbons- 1) Alkanes Alkanes are: “Straight chain" hydrocarbons where ALL the carbon atoms are connected by SINGLE bonds. An Alkane is said to be SATURATED as each carbon bonding site is attached to another atom. * They are very flammable!! Eg. Methane, Butane, Propane, Octane

Alkanes… See the pattern? Structural Formula Molecular Formula

HEPTANE! 1 Meth- 2 Eth- 3 Prop- 4 But- 5 Pent- 6 Hex- 7 Hept- 8 Oct- 9 Number of Carbon Atoms Root Word 1 Meth- 2 Eth- 3 Prop- 4 But- 5 Pent- 6 Hex- 7 Hept- 8 Oct- 9 Non- 10 Dec- Alkanes are named by…   The root of the name tells you how many Carbon atoms make up the backbone, and ending the name! with –ane. Ie. If there are 7 carbons in the backbone of a straight chain molecule (with all single bonds between the carbons) – the molecule is called... HEPTANE!

Practice Time!! Determine the number of carbon atoms in the longest chain and name the alkane! (Assume all the C's are saturated with H's – it would just too long to write them all in!) Heptane Heptane Octane Decane

Branched Alkanes… See any pattern?

Some Functional Groups that can be attached to an Alkane = Alkyl Groups methyl ethyl propyl Halogen Prefix CH3 C2H5  CH2CH3 CH3CH2CH2 Cl “Chloro” Br “Bromo” F “Flouro”

Branched Alkanes… See The pattern Now??

How about these ones?

How about these ones?

Naming Branched Alkanes!! The stem or the root name is the longest continuous carbon chain. Find it and name it first… it does not have to be in a straight line! 1 Meth 2 Eth 3 Prop 4 But 5 Pent 6 Hex 7 Hept There are six carbons in the longest chain therefore it is a HEXANE!

2. The Alkyl groups are named next in alphabetical order. methyl ethyl propyl Halogen CH3 C2H5  CH3CH2CH2 Cl– There is an ethyl- group and a chloro- group, therefore it is a “chloro ethyl hexane”

Use prefixes to tell how many of each substituted group are present (IF NOT ONE!) 2 di 3 tri 4 tetra 5 penta 6 hexa In our example, There is only 1 chloro group, and 1 Ethyl group… so no need for any prefixes! (If there had been 2 chloro groups – we would have said di chloro!!)

2-chloro-3-ethylhexane 4. Number the C atoms of the chain from the end that will give the substituted groups the lowest combination of numbers. (Number from the same end for all substituted groups on the chain!!!) The chain can be numbered so that the chloro and ethyl are either on the “2 and 3 carbon” or on the “4 and 5 carbon”… THEREFORE this molecule is: 2-chloro-3-ethylhexane Note: Numbers and letters are separated with “-” (dash) and numbers are separated with a “,” (comma)

5-ethyl-3, 4-dimethylheptane Name the following: 1, 2- dibromobutane 5-ethyl-3, 4-dimethylheptane

Try Some!! 3-methyl hexane 4-ethyl heptane 3-ethyl octane 4-methyl nonane 3-methyl heptane

Hebden Pg. 220 5#a,d,e #6a Hebden Pg 221# 8/9 (a,c,e,g,i of each) Try Some Practise! Hebden Pg. 220 5#a,d,e #6a Hebden Pg 221# 8/9 (a,c,e,g,i of each)